Remove individual 'New in version 2.5' marks for commands

Instead, have a global versionadded: 2.5 at the start of the file, noting
that the entire set of Fabric commands & support were added in 2.5.
Improvements to Pootle Fabric docs

Fix typos and improve wording; clarify root password (can be sudo)
more specifics on required software and dependencies
eliminate duplication of instructions on how to run fabric commands
various other cleanups
Eliminate hardcoded python version
Fix up permissions / ownership / groups of project_path subdirs

Make sure that translations/repositories/logs are writable by server group
Eliminate confusing use of mkdir -m (it works differently than you think)
Make sure that virtualenv/source are world-readable even with umask 077
Create database even when not using MySQL root for Pootle

If CREATE DATABASE fails (non-root, or at least not granted all) then try
creating the database as root, granting all privileges in the DB to the
configured user.