[Scenario] Strip out obsolete tagging UI

Remove user interface associated with Activity Types
and Tags which is to be replaced by new user
interface per nasa/MCT-Plugins#129.
[Scenario] Change layout for new tag/type UI
[Scenario] Add edit button to tag UI
[Scenario] Disable edit button in tagging UI

Respond to setMutable by enabling/disabling the button
used to open the editing dialog in the Info View's
Activity Tag editing UI.
[Scenario] Add dialog for tag selection

Adds a dialog for selecting tag associations for an
activity, as described in nasa/MCT-Plugins#129.

Additionally, refactors the manner in which repository
information is communicated down to custom visual
controls for tag editing. Specifically, repositories
are identified explicitly, as are component type infos
for repository contents; this replaces prior approach,
which identified both repositories and relevant
contents by capability. (This was more dynamic, but
less explicit, and sometimes error prone.)

This change incidentally resolves nasa/MCT-Plugins#132.

This change will additionally simplify
nasa/MCT-Plugins#134, by removing the assumption (in
the code for the visual control in Activity's Info View)
that repositories will be located at the bootstrap
level.
[Scenario] Pack tag selection dialog

Pack tag selection dialog after it is populated,
to avoid appearing very small on display.
[Scenario] Lay out check boxes in tag select dialog
[Scenario] Add OK/cancel to tag selection dialog
[Scenario] Add padding to tag selection dialog
[Scenario] Fix layout of tag selection dialog
[Scenario] Update activity control from tag select dialog
[Scenario] Rename generated parameter
[Scenario] Class-level JavaDoc for tag selection dialog
[Scenario] Position tag editing button

Move tag editing button to top-right, as indicated
in nasa/MCT-Plugins#135.
[Scenario] Remove unused fields
[Scenario] Make tag selection dialog modal

Make tag selection dialog (created by choosing
to edit an Activity's tags or activity types
from the Info View) document modal. This prevents,
among other things, the user from popping up
multiple such dialogs.
Merge pull request #140 from VWoeltjen/mctPlugins129

[Scenario] Revise activity tagging UI