XD-1229 Initial Yeoman project initialization

* Add AngularUI Router dependency
XD-1229 Add images, fonts, favicon, views
XD-1229 Add UI-Router routes; Add E2E test + Infrastructure
Add LESS support + UI Admin Styles

* Major improvement - instead of customizing Bootrap's `variables.less`, we import its styles into `main.less` and customize only the variables that changed. That way we can easily upgrade Bootstrap in the future
XD-1229 Add ListDefintion Support (Service + Controller)
XD-1229 Fix a `grunt-usemin` issue with images in CSS files

* Use fix as detailed here: https://github.com/yeoman/yeoman/issues/824#issuecomment-29137057
* See also issue: https://github.com/yeoman/grunt-usemin/issues/242
XD-1229 Exclude vendor CSS

* We already import the Bootstrap CSS via `main.less`
XD-1229 Don't use port 8080 for Karma tests

* Minimize conflicts with Tomcat
XD-1229 Add "Loading Indicator" support using `angular-busy`
XD-1229 Add Job launch support + Growl support + define XD Server URL globally

* Use Bootstrap fonts from the distribution
* Add Job launch support
XD-1229 Update `.gitignore`
XD-1229 Update Nodejs dependencies, fix test dependencies

* Running `npm install` should install all relevant dependencies from `package.json`
XD-1229 Add basic Gradle build support
XD-1229 Import CSS files as LESS resources in `main.less`

* Otherwise you run into minification issues as Grunt's nsmin does not consider those CSS files
XD-1229 Rename `admin-ui2` to `admin-ui`

* rename old `admin-ui` to `admin-ui-old`
XD-1229 Improve resolving of the admin-ui URLs

* http://localhost:9393/admin-ui --> http://localhost:9393/admin-ui/#/jobs/definitions
* http://localhost:9393/admin-ui/ --> http://localhost:9393/admin-ui/#/jobs/definitions
XD-1229 Add task `cleanDist`
XD-1229 Improve Gradle build - Depend on `spring-xd-dirt:backgroundAdminServer`
XD-1229 Fix `xd.ui.home` in `application.yml`

* `xd.ui.home` in `application.yml` should contain a trailing slash
XD-1229 Add `grunt-bower-task` to Grunt build

* Allow Bower to be called via Grunt
* Test that the UI builds with `gradle npmInstall installGrunt build`