First basic integration with MwebEvents

Just added the gem and the migrations to get it working.

refs #1115
Update MwebEvents and require its assets properly

Now all partials rendered by the layouts must include `main_app.` before any
route path helper that is called. Since these layouts are used when rendering
the views on MwebEvents, we have to add `main_app.` to tell rails that the route
helpers are from the main application and not from the gem.
Should try to find a better solution in the future.

refs #1115
Set an specific layout for events

refs #1115
Associate Space with events from MwebEvents

Only the view index was changed so far to use the new MwebEvents::Event
model.

refs #1115
Adapt and clean up old events

Removed all references to Participant and relationships between events and
anything other than spaces (posts and attachments were related to events).

The old events model/controller/views are now space_events, since they will be
used for events inside spaces only. Several things still have to be removed from
these events to clean it up.

Events will only belong to spaces for now, and the application will use as much
as possible from MwebEvents. What will be left in the application will be only
the necessary to adapt the gem to Mconf-Web.

refs #1115
Remove views and actions not used anymore in events

Instead of the actions and views removed we will now use the actions and views
from MwebEvents. The events are now a "global" resource, as are spaces. They
are currently always associated with spaces, but it will not be required in the
future.

refs #1115
Add permissions and update migrations for MwebEvents

Permission control added in models/ability replicating what was made in the
gem.

refs #1115
First version of a customized index for events

Not entirely finished yet. Uses the same style used in the index for spaces,
with a few adaptations.
Includes changes in the index for spaces: moved some styles to base classes
that are now used also in the index for events.

refs #1115
Correct typo on partial variable name
Populate tasks for new events
Include mweb_events helpers
Finish a first version of events/index

refs #1115
Custom header on events/show, using the default from other pages

refs #1115
Add migration to migrate events to MwebEvents

Had to rename a few migrations because we have to migrate the events after
creating tables for MwebEvents but before removing the old events.

refs #1115
Remove last table and images for old events

refs #1115
Removed friendly id slug and updated to last migrations from mweb-events engine
Adding recent activity for new events
Adding pagination support
Remove last references to old events, hopefully all of them

refs #1115
Fixing public activities for new events

refs #1115