Make the composer and TopicCreator use category id instead of category name

Also fixes #1171
Added backwards compatibility for topic creation
FIX: Index out of range error

Fixes 'index out of range error' that occurs when viewing a user's
profile page when they haven't yet posted a reply or created a topic
and is @mentioned in a topic.
ATTENTION NEIL, comment out a big pile of importer specs, this is code we never use and running a big slug of tests to ensure it keeps working is pointless.
We need to decide what we do with this. Either we get import/export working and used or strip it out till ready.
No point slowing down the test suite and fixing regressions in code this code
move seed fu to work with my branch of seed fu while https://github.com/mbleigh/seed-fu/pull/54 is being decided
notify moderators now goes to the "community" user, that saves our poor mods from a flood of pms
if any staff respond to a pm they are automatically added to the list of recipients and will start
getting email notifications
rename system_username to site_contact_username , system_user is a special user with -1 id that is only used for certain admin tasks

for example system_user will autoclose stuff if needed, it will delete stubs and be the target for flag pms
update annotations
fix broken build
hack to allow for PMs with no users for flagging needs
shorter user deletion text
better rename the old values otherwise, trouble
playing with my script, feel free to ignore
missed a few renames
FIX: recover post by a non-staff user fails because the post is not unique. Uniqueness check shouldn't happen when recovering a deleted post.
proper content-disposition header when downloading attachments
Merge pull request #1417 from ZogStriP/content-disposition

proper content-disposition header when downloading attachments
Merge pull request #1402 from LaunchAcademy/fix_index_out_of_range_error

FIX: Index out of range error
Merge pull request #1215 from Elegios/composer_use_category_id

Make the composer and TopicCreator use category id instead of category name
Fix IE9 bug in browser-update. Unable to get value of the property 'insertBefore': object is null or undefined
Remove brackets from `username_filters[]` URL