Cleanups on Fabric script
Fabric: Add new drop_deployment command
Docs: Move 2.5.1 changelog to the corresponding release notes
Docs: Move 2.5.0 changelog to the corresponding release notes
Docs: Remove 2.1.6 from changelog

All data is already present in the release notes
Placeables: Use Translate Toolkit built from repo instead of package

This is necessary since the latest Translate Toolkit package doesn't include
some changes done to placeables code that might be necessary to use.
Placeables: Highlight and copy with mouse click in editor

Fixes bug 3146
Placeables: Add tooltip indicating type of placeable
Placeables: Replace fancy_highlight with highlight_placeables templatetag

Keeping highlight_placeables JavaScript equivalent function for now since it
is used to highlight the view rows on the client browsers.
Add a dialog with the keyboard shortcuts list in the editor page

Fixes bug 2589
Placeables: Cycle forward through existing placeables using keyboard shortcut

Mimics Virtaal behavior:

* If the last placeable is selected then all placeables are unselected,
* If no placeable is selected then selects the first one,
* If any other placeable is selected then selects the next one.
Placeables: Cycle back through existing placeables using keyboard shortcut

Mimics Virtaal behavior:

* If the first placeable is selected then all placeables are unselected,
* If no placeable is selected then selects the last one,
* If any other placeable is selected then selects the previous one.
Placeables: Copy placeable to translation field using keyboard shortcut

Mimics Virtaal behavior:

* If there is a selected placeable then copy it to the translation field, in
  the position where the cursor is, or at the beginning of the line if there
  is no cursor.
Remove stray os.close(fd)

A fallout from 2bc49e00d7485dabb5659c8104d5224ec1cad451.
Minor cleanups on views, templates and url patterns
Split foreign relations in initial migrations into separate migrations

Postgres is more of a stickler when it comes to constraints. Since we
can't defer constraint creation, nor defer its validation over multiple
migrations, we have to split the migrations.
This probably won't be a problem in Django 1.7.
We are also splitting the migrations on existing installs (checking for
existing table/column names)
Fixes #3160
Travis: Split dependencies into their own file

This avoids extra dependencies when building the package outside travis.
Travis: Add a travis-specific settings file
Travis: Add postgres to the testing matrix
Travis: Add mysql to the testing matrix