Add functional tests for admin navigation bar and menus

issue #2273
- Check that menu nav items exist
- Check that menu nav items are labeled correctly
- Check that menu nav items have correct URLs
Added populate last login time

closes #2515
- sets last_login when user is saved if user status changed to active
- added integration test in user Basic Operations
Fixed check for a theme's custom error.hbs:

Closes #2513
- Checks for property `error.hbs` on active theme
- Added unit test to ensure `error` view is rendered when activeTheme has
  a custom error template.
- Removed unused variable, `userErrorTemplatePath` from errorHandler
- Refactored errorHandler.`updateActiveTheme` to take one argument, the new active theme, and to then check if the active theme has an error.hbs
- Changed errorHandler unit test to use rewire for mocking config.
Update README & Contributing with details of stable branch
Adding .bowerrc

If no .bowerrc file is found in the current folder it seems to lookup if one exists in parent folders. Thus, we need to use .bowerrc in order to avoid problems.
Merge pull request #2386 from manuelmitasch/add-bowerrc
Server start refactor, route tests use ghost app

closes #2442, issue #2182

- Server start refactored - messaging is just messaging, deferred resolves the httpserver so that the connection can be closed
- Updated travis config to set node env
- Updated example config to be less travis-specific
- Route tests updated to use this new functionality
- Grunt test-routes simplified
Merge pull request #2500 from ErisDS/issue-2442

[WIP] Server start refactor, route tests use ghost app
Merge pull request #2450 from jaswilli/issue-2273

Add functional tests for admin navigation bar and menus
Merge pull request #2516 from novaugust/last_login

Added populate last login time per #2515
Ghost footer outputs minified jquery in production

Closes #2524

- Added minifying jquery in grunt prod task

- Add test coverage for altered jquery
Remove second PUT request on image save

closes #2557
- replaced model.save() with model.set()
Merge pull request #2517 from novaugust/theme_error

Fixed check for a theme's custom error.hbs
Merge pull request #2558 from sebgie/build-fix

Remove second PUT request on image save
Merge pull request #2545 from joeljfischer/minify-jquery

[WIP] Ghost footer outputs minified jquery