add cli tool for rendering a map to an image
show default values and allow setting the output filename
add xcode project for render cli util
allow setting the cache database
don't provide a default value for the stylesheet file
fix crashes when running in non-continuous mode
set rendering mode so that we can skip intermediate renders for static images
fix error in non-debug builds
fix CachingHTTPFileSource::clearLoop
Merge pull request #721 from mapbox/clear-loop

fix CachingHTTPFileSource::clearLoop
don't assing nullptr to std::string
never create core profile contexts; their API is subtly different

(e.g. glGetString(GL_EXTENSIONS) doesn't work, you'd have to use glGetStringi(GL_EXTENSIONS, ...);)
automatically copy the certificate bundle
indicate submodule setup in common header of install info
Update READMD.md for OS X Yosemite
Make file request overridable by platform implementations

refs #579: Android can now rename AssetRequest to FileRequest and implement it differently
change file:// to asset:// to indicate that they aren't arbitrary files

refs #579
change comment and cache value
Merge pull request #723 from mapbox/overridable-file-request

Make FileRequest overridable by platform implementations
Merge pull request #718 from mapbox/cli-render

CLI render