Rule preventing assigning an ivar outside of getters/setters/init.
Fix comments from review for ObjCAssignIvarOutsideAccessorsRuleTest
Fix comments from review.

Use _ for ivars.
Move string utilities into StdUtil.
Minor style changes.
Add back mistakenly missing test case file.
Make assorted utilities inline and fix issue with capitalizing a zero length string
Create StdUtil.cpp and move some helpers to it. Rename capitalize to capitalizeFirstLetter
Cleanup dogfooding errors
Fix up tests for assign ivars
Move ObjCAssignIvarOutsideAccessorsRuleTest from migration to convention
Merge branch 'assign-ivars' of https://github.com/aleffert/oclint into aleffert-assign-ivars