Tinybox inclusion for changelog entry

- Changelog entry won't be saved to the ETT database. Instead, the user will be
  prompted for the changelog when she/he decides to submit a build.

When the build is ready to be submitted, show a box that allows the user to add a changelog
![changelog2](https://f.cloud.github.com/assets/630746/948028/4acf67aa-035f-11e3-9e3c-5bb0480e7309.png)

If the package is not 'InProgress', does not have an assignee, or the Git-URL is not specified, then don't allow the user to submit the build to the mead-scheduler.
![changelog3](https://f.cloud.github.com/assets/630746/948029/4acf3528-035f-11e3-8e20-c29917e84969.png)