Bug 937673 - Modify groups model to allow user-created curated groups

* Add flags for functional area, members_can_leave, visible
* Get rid of system, auto_complete, and related fields
Bug 938184 - Don't allow creating groups while editing user profile

Part of the changes for curated groups is that groups will only be
creatable from the groups list page, so only allow people editing
their profiles to select groups that already exist.

The tag-it library that was being used to implement the groups
selection could not easily be configured or modified to prevent
users from selecting non-existent items, so the groups field
was changed to use django-selectable. Styling was added to make
the django-selectable field look like the current tag-it fields,
which are still being used for e.g. skills and languages.
Remove some unused code from groups/forms.py
[Fix Bug 938674] Added Create Group button the Groups list page (+2 squashed commits)

only translating the words in the create group button

[Fix Bug 938674] Added Create Group button the Groups list page
merging Bug 937673 - Modify groups model to allow user-created curated groups
merging: Bug 938184 - Don't allow creating groups while editing user profile

Part of the changes for curated groups is that groups will only be
creatable from the groups list page, so only allow people editing
their profiles to select groups that already exist.

The tag-it library that was being used to implement the groups
selection could not easily be configured or modified to prevent
users from selecting non-existent items, so the groups field
was changed to use django-selectable. Styling was added to make
the django-selectable field look like the current tag-it fields,
which are still being used for e.g. skills and languages.
merging:  Remove some unused code from groups/forms.py
Merge remote-tracking branch 'upstream/pr/726' into curatedgroups-merge
Update migrations
Merge pull request #1 from dpoirier/curatedgroups-merge

Update migrations for curatedgroups-merge
Fix group editing
Merge pull request #2 from dpoirier/fix-group-editing

Fix group editing
Merge branch 'curatedgroups-merge' into curatedgroups
Merge remote-tracking branch 'mozilla/master' into curatedgroups

Conflicts:
	mozillians/settings/base.py
	mozillians/templates/phonebook/edit_profile.html
[Bug 936569] Curated Groups: Allow users to create/manage groups
[Bug 936569] merge curatedgroups branch into master, thanks to @dpoirier and @wbowling

Bug 951840, bug 936570, bug 937673, bug 938184, bug 938674, bug 938680,
bug 938695, bug 938723, bug 939127, bug 947271, bug 948491, bug 948640,
and bug 951515 are fixed by this patch.
[Fix Bug 959131] Add unidecode 0.4.14 to vendor-local/lib
Bug 950242 - Admin management of group membership

Allow Django admins to manage group members as inlines on the group's
admin page.

This will work fine for reasonable-sized groups, but will get unwieldy
when groups get really large.  We might be better off managing group
membership from a user's page, since a user is unlikely to belong to
so many groups that that would get too big. Unfortunately, Django currently
doesn't support nested inlines in the admin, which would be required
because we already implement the user admin by making the userprofile
an inline on the user page, and the membership would have to be an
inline on the userprofile.

A better way for admins to manage memberships might be directly in
the GroupMembership model. To make that easier, I've added a search
field to that admin changelist page that searches on a bunch of fields
in the groups and users associated with the membership records. It
shouldn't be hard to find a user's memberships or membership in a
group, or just add a new membership.

Fixes bug 950242
Bug 959131 - Make unidecode a git submodule
Merge pull request #762 from caktus/submodule-for-unidecode

Submodule for unidecode