Quoting attachment filename

Attachment file name was not surrounded by quotes.
If an attachment was "picture of me.png", the browser was proposing to
download a file named "picture".

Change-Id: I17a1f8ca3b7ef44171c4977bacc9045e4695e18c
Closes-bug: #1245927
Updates tox.ini to use new features

Reasons:
 - tox update v1.6

Changes:
 - tox 1.6 allows us to skip the sdist step, which is slow.
 - It also allows us to override the install line. In this case, it's
   important as it allows us to stop getting pre-release software we
   weren't asking for.

Original patch by Monty Taylor, talked about here:
http://lists.openstack.org/pipermail/openstack-dev/2013-September/015495.html

Change-Id: I0b2da3369ec303b9997305f602e6c444cafe14b0
Merge "Updates tox.ini to use new features"
Merge "Quoting attachment filename"