Add default value

Change documentation
Add default value for direct mapping
Add podspec file
Very minor typo fix
Merge pull request #211 from ColinEberhardt/master

Very minor typo fix
Return value for [NSNull null] if key is null in mtl_valueMappingTransformer
Merge pull request #212 from StyleShare/master

Fix a crash when key is null in mtl_valueMappingTransformer
2014, yo!
Merge pull request #218 from dataxpress/master

2014, yo!
MTLManagedObjectAdapter: Fix a bug where errors are silently handled

It was using `error` but this error is replaced later in the method and never
passed as an error.

```objective-c
if (error != NULL) {
    *error = tmpError;
}
```
MTLManagedObjectAdapter: Add tests for validating values
MTLManagedObjectAdapter: Fixes an issue with validate for insert

Fixes an issue where validation for insert would return a deleted
managed object without an error

When it does this in combination with
`relationshipModelClassesByPropertyKey` CoreData could raise an
exception for using setting child’s in a different context (because it
doesn’t have a context)
Merge pull request #220 from kylef/bug/managed-object-adapter/silent-error

MTLManagedObjectAdapter: Fix a bug where errors are silently handled
Fixed 'guarantee' typo
Merge pull request #224 from eliperkins/patch-1

Fixed 'guarantee' typo
++xcconfigs
Remove static qualifier from error codes

Otherwise Xcode considers them unused variables per
-Wunused-const-variable
Remove unnecessary error code
Merge pull request #227 from MantleFramework/bump-xcconfigs

++xcconfigs
Merge remote-tracking branch 'upstream/master'
Fix a crash when an invalid keypath is used