instancetype love.
Revert singleton method.
fixed TJ's bug in using main context instead of contextOrNil
changed behavior of checkClass method - empty server parameters will be turned to nil in the NSManagedObjective subclasses
added explanation comment and updated tests
Merge branch 'master' of github.com:MattFoley/CoreDataManager-iOS
added a check on unique key in testImportWithCustomMapperAndAnEmptyInputValue
Merge pull request #1 from seanwolter/master

updates to checkClass (including tests and comments in VIManagedObjectAdditions header)
Merge sean's changes.
merged TJ's addition of numberFormatter - needs tests
wrestling with git and TJ's reverts
NSNumberFormatter additions.
silly merge errors
fixed header from git merge back and forth
fixed more merge errors and added DISPATCH_ONCE for default formatters in place of checking for null
removed default number formatter from default mapper to avoid changing NSNumbers to NSStrings unintentionally
Merge pull request #15 from seanwolter/master

TJ's addition of number formatter and bug fixes and more tests