Incorporate CocoaPods into the project.

This branch and effort was kicked off at [Coder Day of Service 2014](https://www.codemontage.com/coder_day). I figured I'd remove ASI as a static library from the project, and add it back in using CocoaPods. Then, once that was complete, my intention was to replace ASI with AFNetworking. But overall, having CocoaPods in the project would make it that much easier to incorporate third-party libraries later on, not just AFNetworking.

However, I've been battling, albeit unsuccessfully, with a linker error for the past 2+ hours. I figured I'd submit what I have so far as a pull request, in the hopes that someone can pull it down and easily spot what the problem is. I tried adding ASI as a CocoaPod to a blank project, and that built and linked just fine. So, I suspect that there's some sort of conflict between the OTM project's configuration and CocoaPods.

The linker errors I'm getting are:

```
Ld /Users/gabe/Programming/OpenTreeMap-iOS/Build/Products/Debug-iphonesimulator/OpenTreeMap.app/OpenTreeMap normal i386
    cd /Users/gabe/Programming/OpenTreeMap-iOS/OpenTreeMap
    setenv IPHONEOS_DEPLOYMENT_TARGET 5.0
    setenv PATH "/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin:/Applications/Xcode.app/Contents/Developer/usr/bin:/usr/local/bin:/Users/gabe/.rvm/gems/ruby-2.0.0-p247/bin:/Users/gabe/.rvm/gems/ruby-2.0.0-p247@global/bin:/Users/gabe/.rvm/rubies/ruby-2.0.0-p247/bin:/Users/gabe/.rvm/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin"
    /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang -arch i386 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator7.0.sdk -L/Users/gabe/Programming/OpenTreeMap-iOS/Build/Products/Debug-iphonesimulator -L/Users/gabe/Programming/OpenTreeMap-iOS/OpenTreeMap/../DerivedData/opentreemap/Build/Products/Release-iphoneos -F/Users/gabe/Programming/OpenTreeMap-iOS/Build/Products/Debug-iphonesimulator -filelist /Users/gabe/Programming/OpenTreeMap-iOS/Build/Intermediates/OpenTreeMap.build/Debug-iphonesimulator/OpenTreeMap.build/Objects-normal/i386/OpenTreeMap.LinkFileList -Xlinker -objc_abi_version -Xlinker 2 -ObjC -all_load -fobjc-arc -fobjc-link-runtime -Xlinker -no_implicit_dylibs -mios-simulator-version-min=5.0 -Xlinker -sectcreate -Xlinker __TEXT -Xlinker __entitlements -Xlinker /Users/gabe/Programming/OpenTreeMap-iOS/Build/Intermediates/OpenTreeMap.build/Debug-iphonesimulator/OpenTreeMap.build/OpenTreeMap.xcent -lz -framework CoreGraphics -framework MobileCoreServices -framework SystemConfiguration -framework CFNetwork -framework Security -framework UIKit -framework Foundation -framework CoreLocation -framework MapKit -lPods -Xlinker -dependency_info -Xlinker /Users/gabe/Programming/OpenTreeMap-iOS/Build/Intermediates/OpenTreeMap.build/Debug-iphonesimulator/OpenTreeMap.build/Objects-normal/i386/OpenTreeMap_dependency_info.dat -o /Users/gabe/Programming/OpenTreeMap-iOS/Build/Products/Debug-iphonesimulator/OpenTreeMap.app/OpenTreeMap

ld: warning: directory not found for option '-L/Users/gabe/Programming/OpenTreeMap-iOS/OpenTreeMap/../DerivedData/opentreemap/Build/Products/Release-iphoneos'
Undefined symbols for architecture i386:
  "_htmlReadFile", referenced from:
      -[ASIWebPageRequest parseAsHTML] in libPods.a(ASIWebPageRequest.o)
  "_htmlReadMemory", referenced from:
      -[ASIWebPageRequest parseAsHTML] in libPods.a(ASIWebPageRequest.o)
  "_xmlBufferCreate", referenced from:
      -[ASIWebPageRequest finishedFetchingExternalResources:] in libPods.a(ASIWebPageRequest.o)
  "_xmlBufferFree", referenced from:
      -[ASIWebPageRequest finishedFetchingExternalResources:] in libPods.a(ASIWebPageRequest.o)
  "_xmlCleanupParser", referenced from:
      -[ASIWebPageRequest finishedFetchingExternalResources:] in libPods.a(ASIWebPageRequest.o)
  "_xmlFree", referenced from:
      -[ASIWebPageRequest readResourceURLs] in libPods.a(ASIWebPageRequest.o)
      -[ASIWebPageRequest updateResourceURLs] in libPods.a(ASIWebPageRequest.o)
  "_xmlFreeDoc", referenced from:
      -[ASIWebPageRequest parseAsHTML] in libPods.a(ASIWebPageRequest.o)
      -[ASIWebPageRequest finishedFetchingExternalResources:] in libPods.a(ASIWebPageRequest.o)
  "_xmlGetCharEncodingName", referenced from:
      -[ASIWebPageRequest encodingName] in libPods.a(ASIWebPageRequest.o)
  "_xmlGetNoNsProp", referenced from:
      -[ASIWebPageRequest readResourceURLs] in libPods.a(ASIWebPageRequest.o)
  "_xmlInitParser", referenced from:
      -[ASIWebPageRequest parseAsHTML] in libPods.a(ASIWebPageRequest.o)
  "_xmlNodeGetContent", referenced from:
      -[ASIWebPageRequest readResourceURLs] in libPods.a(ASIWebPageRequest.o)
      -[ASIWebPageRequest updateResourceURLs] in libPods.a(ASIWebPageRequest.o)
  "_xmlNodeSetContent", referenced from:
      -[ASIWebPageRequest updateResourceURLs] in libPods.a(ASIWebPageRequest.o)
  "_xmlSaveClose", referenced from:
      -[ASIWebPageRequest finishedFetchingExternalResources:] in libPods.a(ASIWebPageRequest.o)
  "_xmlSaveDoc", referenced from:
      -[ASIWebPageRequest finishedFetchingExternalResources:] in libPods.a(ASIWebPageRequest.o)
  "_xmlSaveToBuffer", referenced from:
      -[ASIWebPageRequest finishedFetchingExternalResources:] in libPods.a(ASIWebPageRequest.o)
  "_xmlSaveToFd", referenced from:
      -[ASIWebPageRequest finishedFetchingExternalResources:] in libPods.a(ASIWebPageRequest.o)
  "_xmlXPathEvalExpression", referenced from:
      -[ASIWebPageRequest readResourceURLs] in libPods.a(ASIWebPageRequest.o)
      -[ASIWebPageRequest updateResourceURLs] in libPods.a(ASIWebPageRequest.o)
  "_xmlXPathFreeContext", referenced from:
      -[ASIWebPageRequest readResourceURLs] in libPods.a(ASIWebPageRequest.o)
      -[ASIWebPageRequest updateResourceURLs] in libPods.a(ASIWebPageRequest.o)
  "_xmlXPathFreeObject", referenced from:
      -[ASIWebPageRequest readResourceURLs] in libPods.a(ASIWebPageRequest.o)
      -[ASIWebPageRequest updateResourceURLs] in libPods.a(ASIWebPageRequest.o)
  "_xmlXPathNewContext", referenced from:
      -[ASIWebPageRequest readResourceURLs] in libPods.a(ASIWebPageRequest.o)
      -[ASIWebPageRequest updateResourceURLs] in libPods.a(ASIWebPageRequest.o)
ld: symbol(s) not found for architecture i386
clang: error: linker command failed with exit code 1 (use -v to see invocation)
```

I hope this is of some value. Either way, I guess it can always just be closed without merging. Thank you for taking a look.