Updated Links

Some links weren't linking to the right directory, prefixed them with
'mycart-plugin/' to link properly.
Sign-up page update

Page now loads up via ajax
Update Customization Page

The customization page has been updated. Wasn't too sure which other
files needed upload so I've replaced everything with a new build.
Customization page can now select colors/font appropriately.
Merge remote-tracking branch 'origin/Phill' into Matt