Adding a flag for Cocoa Pods users

Using the Parse framework and SDWebImage frameworks installed via Cocoa Pods gives the same error as described in the Alternatively section of the Add Linker Flag section in this Readme.
I found a solution here : http://www.deanmao.com/2012/12/31/linker-error-using-cocoapods/
Merge pull request #879 from dulgan/patch-1

Adding a flag for Cocoa Pods users
Updated code sample to not use deprecated api
Merge pull request #890 from kyleclegg/master

Updated key filter sample code
minor spelling (forth->fourth)
Merge pull request #893 from asparagui/sp_fixes

minor spelling (forth->fourth)
Add a method to copy a cached image if it exists
Use hard links instead
Switch to built in XCTest async
Fix multiple requests for same image and then canceling one
Cancel the download operation if it's the last token to be canceled
Move progress / completion handler logic to the operation
Don't create a new image for each completion block
Add back some required locking
Switch to Xcode 6 async tests