Actually call the then block when nil is returned

Fixes #16.

Whoops!

Tag 0.9.5
Fixes -Wshadow and -Wsign-conversion compiler warnings.
Merge pull request #19 from realestate-com-au/bug/compiler-warnings

Fixes -Wshadow and -Wsign-conversion compiler warnings.
Remove macros.m and use objective-c runtime to hold references.
Merge pull request #10 from mackross/master

Replace __anti_arc macros with objc runtime object association to keep alive for proper lifetime
Social framework integration
removed unnecessary import
Merge pull request #20 from krzysztofzablocki/master

Social framework integration
Minor SocialFramework corrections
If error is thrown during ctor don't nest it
Fix compile error if nothing else @imported before

Reorder includes in ./tests to detect this in future.
Merge remote-tracking branch 'upstream/master'