Merge branch 'release/v0.20.0-rc1'
Merge branch 'release/0.20.0'
Drop pre from README.md install instructions
Merge branch 'release/0.20.1'
Adjust version and tag in Podspec for release
Merge branch 'release/0.20.2'
Merge branch 'release/0.20.3'
Merge branch 'release/0.21.0'
Fix bad links in the documentation breakout
Bump dependencies to fix build
Fix issue with objectManager references in test helper
Add conditional compilation around `connectionTestExpectation` to avoid unused variable warning
Fix inability to complete value transformations when using a nested mapping. closes #1656
Honor passed in sqlite options when creating persistent store - this is needed to control the journal_mode in ios7 and osx 10.9.   See https://developer.apple.com/library/mac/releasenotes/DataManagement/WhatsNew_CoreData_OSX/#//apple_ref/doc/uid/TP40013395-CH1-SW1.
Bump version to 0.22.0
Update RKValueTransformers to v1.0.1
Update TransitionKit dependency to 2.0
Update CocoaPods to 0.28.0
Bump Pod dependencies
Add support for serializing values to null. closes #669, closes #1311