Merge pull request #41 from mugginsoft/master

GC support and test targets
Have Xcode 4.5.2 clean up project + run iOS tests with JSONKit
Tests: gather all JSON loading in a single [GRMustacheTestBase JSONObjectWithData:error:] method
Tests: naive support for single line comments in JSON test suites
Restore comments in JSON files (revert 4ce4b2fb208fc193e0fb216aba614465559280fd by @mugginsoft)
Fix typo in Guides/sample_code/README.md
Fix a memory leak in tests
v6.1.4