Adds quick implementation for target action definition of events.
Fix unit test.
Add nil check.
Refactor event handling.
Add TBStateMachineEventHandler class.
Add action and guard to TBStateMachineTransition.
TBStateMachine handles actions and guards when switching states.
Updated unit tests.

Relates to issues #2, #3
Raise exception when name is nil or "" when initializing TBStateMachineEventHandler.
Update unit test.
Update documentation.
Update unit tests.
Fix execution order of enter, exit and action blocks.
Cleanup unit tests.
Update unit tests.
Update change log and .podspec.
Update unit tests.
Fix unit test by adding missing initialization of flags.
Update README.md
Change TBStateMachineParallelWrapper to accept only TBStateMachine instances.
Update REAME.md
Update README.md
Cleanup code.
Add event queue to TBStateMachine.
Add event queuing.
Update unit tests.

Refers to enhancement #4
Update documentation.

Relates to enhancement #4.