Fix PostgreSQL database restoration problem (#4217)

Use psql instead of pg_restore to restore SQL dump file.
Fix paths to the Contents Markdown pages
Increase snippet content column size.

This will fix issue #3904
Issue 3599: Add snippets_enabled flag to projects for API

s 3599: Add snippets_enabled flag to projects for API

Replace missing comma
When stopped correctly there should be no warning about a missing socket file.
Make the installation guide easier to follow for non-unix people.
Update api.js.coffee

CoffeeScript doesn't like that
add db index for authentication_token column in users table
Fix spelling error and make sure you never log in as git user so you never have to logout to run sudo.
Create uploads dir otherwise backup fails. Fix #4304
Remove unused, but slow code
Merge pull request #4279 from barendt/patch-2

Fix paths to the Contents Markdown pages
Fix Issue.open_for
contributing guideline updates

* updated close policy
* added line on courtesy & respect to volunteers
* request that issue information be placed in first issue post
Use navless layout for snippets page
create UsersGroup entity. Modify ability to check group owners instead one owner
Added UsersGroup validations. Added ability to add UsersGroup to group via UI
UsersGroup specs. Fixed db/schema
Add UsersGroup relation to be respected by abilities and Project#team
Use project.team over project.users