Buildbot try client --url flag

Added a --url option to the buildbot try client. When specified it will print out the url of the build. If --url is specified then the client will wait for the build to start then print the url. It is relatively impossible to print out the url of the build before the build has actually started. If --wait is also specified then the url will be printed at the end of the builds right before the program exits.

Here is an example of it being used. http://pastebin.com/VryVdtRB