Added the ability to select a project, and report billable/non billable according to the project's default settings

Hi,

I've added a feature I was personally missing - the ability to select a project, and report a time entry as billable according to the selected project's settings.

I've currently integrated this functionality only to asana, but it can be easily added to pivotal/teamweek/github.
The styling could use some work - but still, it is better than not having this feature at all.

Please review.

Thanks!