Minimum python version for flower and therefore 0.9.0

[Ed McDonagh]

Flower depends on Tornado which requires an up to date SSL module which requires Python 2.7.9 or later.

Need to add to docs some guidance as to how to upgrade Python if older than 2.7.9.

A good first step would be to check with python -V

Also, flower requires a more recent version of setuptools than some users may be using (v3.6 is too old, I don't know what the minimum version is).

Can be fixed with pip install setuptools -U

For Ubuntu users,

• Trusty/14.04LTS would be tool old (Python 2.7.5)
• Xenial/16.04LTS and later would be ok (Python 2.7.11 and later)

Marking as 0.9.1, but needs to go in the 0.9.0 documentation too.

[Ed McDonagh]

code block did't work. Refs #747. [skip ci] docs only.

→ <<cset cccf5f406096>>

[Ed McDonagh]

Attempt to get just enough information in to move forward without writing a new section... Refs #747. [skip ci] docs only.

→ <<cset a17af5ebe25f>>

[Ed McDonagh]

Added hint to find db user if migrating to upgrade Python. Refs #747. [skip ci] docs only.

→ <<cset c54c2eefdb00>>

[Ed McDonagh]

Initial attempt to do upgrade docs that include 0.7.4 onwards. Refs #747. [skip ci] docs only.

→ <<cset 4b43515297dd>>

[Ed McDonagh]

Merged in issue749minordocsupdates (pull request #302)

Docs updates preparing for 0.9.1

Fixes #747, #749. Refs #751

→ <<cset 5e8641770fcb>>

[Ed McDonagh]

Adding ref #747, #749 to changes

→ <<cset 94360bc320b7>>