Autosaving thread data

It will autosave all the elements with class `sf_autosave` as post meta
with key `_sf_autosave_$element_id`. Currenly it autosave cc, bcc and reply box.

Currently it don't support autosave functionality in new threads
Sending element ID rather than name during autosave
Corrected WP coding standard
Auto save also new tickets
Enable autosave for post title and respondents in draft tickets only
Redesigned submission form
Set E-Mail account as empty be default if not specified
Check for E-Mail account ID existence before accessing a E-Mail account
Show E-Mail account drop box always in case it is not set

Earlier it was only shown new ticket post. It will help when tickets are
created without a E-Mail account. e.g. support form or auto-drafted
tickets
Removed unnecessary code
Moved inline CSS to style sheet
Merge pull request #155 from VarunAgw/submission-form

Redesigned submission form.
Merge pull request #138 from VarunAgw/auto-save

Autosaving thread data
Merge pull request #156 from VarunAgw/minor-change

Group of minor changes.
Saving attachment ID as meta data of reply

Earlier reply id was saved as post_parent of attachment. But since an
attachment cannot have more than one parent, more than one reply cannot
use any specific attachment
Updating attachment database scehma on plugin update
Serving attachment file securely through PHP
Prevent inserting a same attachment twice in a reply
Add some random characters to uploaded files

This is to prevent direct access by guessing its name
Adding random characters to only files uploaded to SupportFlow

Earlier it cover all file including files not uploaded to SupportFlow