Horizontal Progress Bar added during for key creation

I have tried implementing the horizontal progress bar during key creation in place of the spinning wheel. The basic template for communication between the background KeyServiceIntent and the foreground KeyServiceIntentHandler has been setup.

The KeyServiceIntent updates the key creation progress step by step and sends messages to the handler. The handler inside KeyServiceIntentHandler catches the messages and thereafter sets the progress in the progress bar.

The progress bar is not smooth enough. People are welcome to improve on it. 

PS: This is my first pull request on gitHub as part of the one-patch rule required to be a potential student for GSoc 2014. I have tried as far possible to adhere to the pre-requisites before submitting a pull request, forgive me if I have missed something and please let me do know about the same.