Add a mock factory method
Add a test for simple return value executions of global namespace functions
Add a test for exceptions thrown for non-allowed functions
Add return docs for some methods
Add a test to verify namespace and prefix behavior
Add a test to verify that validateMethodName will throw an exception if the function does not exist
Fill in methods in FunctionLibWrapper class to pass tests
Empty classes to abstract pcntl and posix functions and empty tests for them too
Tests for posix and pcntl wrappers