Merge branch 'release/0.26.1.21' into develop
A new target to fast deploy only the environment.
Update `pnotify` to 1.2.2 (via github source) to style as `bootstrap3`. 

Be sure this doesn't crash if using CDNs, the 1.2.2 version is not yet published. 
Thus, this will fallback to bootstrap 2 but at least it will be still usable.
Implement a bare announcement system, for all users and staff members.

Move the notifications code in a dedicated file. Add the constance defaults and documentation.
SCSS updates / cleanups.

Remove pnotify overrides, they don't work with BS3.
Move "various-overrides" later in the common SCSS, this allows it to benefit from 1flow/BS3 variables.
version bump for 0.26.2.
Merge branch 'release/0.26.2' into develop
Merge branch 'release/0.26.2'
Announcements fixes.

Don't crash `constance` config in the admin because of `ugettext_lazy()` (too bad it doesn't work...), and always insert a real space between prefix and messages in the announcement.
version bump for 0.26.2.1.
Merge branch 'release/0.26.2.1'