Added ability to create EC2 volume from snapshot

ec2_vol module now takes optional snapshot argument
Added relevant module argument handler and documentation
Simplified p.poll handling
Merge pull request #4508 from willthames/ec2_vol_snapshot

Added ability to create EC2 volume from snapshot
Add ec2_vol snapshot example from #4189
Fixes #5750 Fail on missing ~/.ssh and ignore accept_hostkey if stricthoskeychecking is off
self.su_user is done earlier in the code path, and is auto-vivified from
su_user_var.  My last PR was only half merged, and when the bug fix for
the su/su_pass typo was merged, the removed line in this commit was
mistakenly reintroduced.
Merge branch 'slow_ssh' of git://github.com/lberruti/ansible into lberruti-slow_ssh
be permissive with BSD with service enabled upper/lower/mixed cases

Signed-off-by: Brian Coca <briancoca+ansible@gmail.com>
Merge pull request #5805 from bcoca/bsd_insensitive

be permissive with BSD with service enabled upper/lower/mixed cases
Fix .ssh/known_hosts path expansion.

In particular, do not rely on the $USER environment variable always existing.
tmux for example seems to clear it, causing lots of invalid messages:
"previous known host file not found"

This broke in commit 80fd22dc, but instead of reverting that commit, we now
fall back to expanding just ~ when $USER is not set.
First commit of the at module being very basic.
Added user option.
Formating and syntax fixes that were pointed out during code review.
Change to dynamically pick up the command from the PATH.
Rough cut implementation based on @resmo's comments.
Rough cut implementation based on @resmo's comments.
Tested implementation adding action option for (add, delete, unique).
Remove unused graphics.
Fix logo scaling on docsite.
Much rejoicing, ansibleworks.com is now ansible.com

Also note AWX is named "Tower" now, as we found that simpler.