bitbake: toaster: add project main edit page

bitbake: toaster: add project main edit page

This is the first commit on the project main edit page.

At this point we have:
* the default settings for a newly created project
* the ability to add targets
* the ability to trigger a build command, and have
the build executed

Project layers now have an optional field, allowing for
removal. Default meta, meta-yocto and meta-yocto-bsp
layers cannot be optional.

We add XHR calls for interactivity in the main page.

(Bitbake rev: 4e438854120cbd10319df1b571ec93e334002325)

Signed-off-by: Alexandru DAMIAN <alexandru.damian@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>