Added the ability to open rows in new tabs.

If proper anchor tags were used, we would be removing the ability to
select text with the mouse, thus we emulate the anchor behaviour.
While this is far from perfect, covers both use-cases (selecting text
and opening links in new tabs) in most of the situations.

Fixes bug 2657.
Do static file collection before building
Remove submitted_by and commented_by from TermUnitForm

This allows to save edited terminology entries, but no data about users is
saved for the edited terminology.

Fixes bug 2743.
READ COMMIT MESSAGE BEFORE UNDOING

Added support for editing the term translation.
Changed term translation widget (tried TextInput but seems not to work well, so using TextArea with 1 row).
Added definition column.
Changed columns width (TODO this impacts on other parts of Pootle. Changing column classes might not to be an option since they are used in Javascript).
See if commented stuff in term_edit template is necessary (at least translator comments seem to be used to save other alternative translations for the term).
READ BEFORE UNDO THIS

Commented code for logging in order to not having too much noise in the console when running the development server and see what is going when editing terminology.