Revert "Remove rescue from channels subscribers"

This reverts commit 43cac2d5e9b212abc475fca6f98fde5dc6614dd2.
Fix firefox button font-sze
Change some channel languages, improve design and spacing
Disable completeness for channels

Fixes issue when completeness_progress is nil

Disabled for now because issues if PG transaction.
We will move it to a worker (#58).
Add submit your project text to channel
Enable hstore
Add start_content field to channel
Add start hero image to channels
Add channel concerns about start content
Show channel content in start page when accessing from a channel
WIP: Start content on channels admin form
Not show inspiration project on channel start page
Add language for channel start page admin
Use language and add markdown editor to channel start page admin
Add success content field to channel
Add success content helpers to channel
Add success content section on channel's admin
Show success content in project success page
Add success content language on channel's admin