Fix #1080: Admin users able to edit Superadmin

Adding a check so superadmin users are not shown on the list when the
user seeing it doesn't have superadmin privileges. Also, if a
non-superadmin user tries to edit a superadmin accessing it directly
from the URL, user gets kicked back to users list.
Updating code to Ushahidi standards
Updating permissions calls
Updating SQL query

Bit of a roundabout way to make sure Superadmin are excluded from admin
user administration for normal admins
Issue #1213 Fixing issue with Sharing plugin

Json_Controller::calculate_center() expencting marker to be an object but
array being passed int by Share_Controller::index(). Not sure if an object
is ever passed to calculate_center(), but this update shouldn't cause a
problem as object properties are acessible using array syntax anyway.
Supressing set_time_limit() call

It generates an error on enviroments with safe_mode enabled, and makes our
scheduler sad.
Fixing spacing
Deleting plugin folder
Housekeeping

Updating helper message to avoid referencing old plugins
Updating upgrade SQL to delete viddler

New instalations won't get viddler on the add-on screen since the plugin
directory is gone. However, existing instalations need to remove it from
the table to avoid a nasty empty line on Add-on screen.

Not sure if we should be checking if the plugin is enabled before doing
this. But then, if the plugin is enabled, the whole thing will break
miserably anyway because its code is gone. Thought I should mention this
as I'm not sure how keen we are on keeping retro-compatibility. :)
Merge pull request #1220 from ditorelo/1214

#1214: Deleting Viddler plugin
Merge pull request #1219 from ditorelo/1189

Fix #1189: set_time_limit() when safe_mode = On
Fix slider JS on alerts page
Fix 'add new category' js #1207
Add hashtag back into twitter queries #1224
Checking if set_time_limit is disabled

We shouldn't try to run it if it is
Merge pull request #1218 from ditorelo/1213b

Issue #1213 Fixing issue with Sharing plugin
Using strstr instead of preg_match

For efficiency-ness. :)
Merge pull request #1228 from ditorelo/1189

set_time_limit() enabled check
Merge remote-tracking branch 'ushahidi/master' into develop

Conflicts:
	sql/upgrade107-108.sql