Add Xcode user-specific files to .gitignore.
Add example classes to demonstrate behaviors.

Examples are not in the podspec's `source_files`.
Example classes demonstrate behaviors which cannot be easily expressed via tests. In this case using `FCYAssertParameterNotNil` should prevent static analyzer warnings about those parameters possibly being nil/null.
Add `analyzer_noreturn` to `-assertFailureWithExpression...`

See http://clang-analyzer.llvm.org/faq.html#custom_assert
`analyzer_noreturn` instructs the analyzer to assume that `-assertFailureWithExpression...` will never return so it is not possible for an execution path to fail the `if (!(condition))` check and then proceed to code following the call to `FCYAssertParameterNotNil`.
Merge pull request #3 from jonah-carbonfive/add_noreturn_annotations

Add noreturn annotations