Grafana 5.0: Add permissions modal for the permissions pages

Implement new url format in alerting

* Add add adapter between io.Writer and log.Logger

* Add phantomjs output to grafana log

* Unexport LogWriterImpl

* Add test for LogWriter

* Make it possible to get phantomjs debug output

* Make it possible to get the configured log level

WIP: Dashboard & Persistent urls - Frontend Step 2

backend for new url structure.

plugins: return table with empty rows array insteaf of nil

Removes slug property in dashboard search responses since this property isn't needed
anymore and it haven't been released to any stable release.

Change the front end route for folders to /dashboards/f/<uid>/<slug of folder title>.
Use new route for deleting dashboard/folder by uid.
Retrieve dashboard/folder by uid when moving or deleting dashboards/folders.

Validates that there are only one folder/dashboard having that slug,
otherwise returns 412 Precondition Failed

WIP: Dashboard & Persistent urls - Frontend Step