NSMutableString(RFStringFormatter) refactoring

RF_formatStringUsingValues is declared as deprecated from now and split
into two different methods as mentioned in #66
Merge branch 'RFStringFormatter'

* RFStringFormatter:
  NSMutableString(RFStringFormatter) refactoring

Conflicts:
	Framework/ROADCore/ROADCore.xcodeproj/project.pbxproj
Merge pull request #335 from ptiz/master

NSMutableString(RFStringFormatter) refactoring for code review #66