Fixed regression in properly gc'ing completed executors.

Review: https://reviews.apache.org/r/14937
Removed unimplemented Dashboard page.

The Dashboard page has been stubbed in the webUI for a while but has not
received any attention yet. It is misleading when a user clicks on the
navigation and doesn't understand what the graphs mean.

The files are not used for anything else, and so they can safely be
removed without affecting the rest of the UI. D3 and Cubism can be
re-added later if they prove useful.

Review: https://reviews.apache.org/r/14657
Fixed GarbageCollectorIntegrationTest.ExitedFramework test.

Review: https://reviews.apache.org/r/14944
Corrected reference to "$routeParams".

It was missing an "a".

Review: http://reviews.apache.org/r/14948
implementation of CLI mesos-upload
cleaner upload status report
Fixed GroupTest.MultipleGroups test.

Review: https://reviews.apache.org/r/14961
MESOS-511 Update documentation home and remove outdated drafts pages.
Added upgrade instructions for 0.15.0.
Updated CHANGELOG for 0.15.0.
Updated version to 0.16.0.
Fixed Makefile to properly refer to README.md.
Renames filenames of documentation to be lowercase and updates some documentation templates for consistency.
Updates link to Spark getting started, and removes linkering textile formatting.
Made Promise have a virtual destructor.

See summary.

From: Benjamin Hindman <benh@berkeley.edu>
Review: https://reviews.apache.org/r/14382
Added the registrar.

From: Benjamin Hindman <benh@berkeley.edu>
Review: https://reviews.apache.org/r/14383
Injected Registrar into the Master and the tests.

From: Benjamin Hindman <benh@berkeley.edu>
Review: https://reviews.apache.org/r/14382
Merge remote-tracking branch 'upstream/master'