move integrated api client to requests library

The integrated api client previously did the HTTPConnection /
HTTPSConnection url parsing dance. In python 2.x HTTPSConnection
doesn't care about SSL certs at all. While not actually an issue for
these tests, it does mean we keep around an example in the code that
uses HTTPSConnection, which will prevent us from creating a hacking
rule to keep those out once the other 4 actual security issues with
HTTPSConnection are removed.

Change-Id: Idd7d5a055600dda663f9c56b39883510f8688b12
Related-Bug: #1188189
Fix Bad except clauses order

Invalid is an ancestor class of AutoDiskConfigDisabledByImage.
If we catch Invalid before, the user will be see a wrong message
"Invalid instance image." instead of "Requested Image has automatic
disk resize disabled."

Change-Id: Idb021c7da01ad7a1af07585be527773d14ff2d20
Reserve 10 migrations for backports

Reserve 10 migrations so that we have the option of backporting fixes
that include a db migration to the stable/juno branch.  We did this
same thing to allow backports and stable/icehouse in
d65139e6f4885869f80ee510f95f733473c579b6.

The choice of 10 migrations is just a magic number.  We haven't used any
of the 10 reserved in previous stable branches, so 10 seems to be enough.

Implements blueprint backportable-db-migrations-kilo

Change-Id: I3e6d2579b22222e51134e517a97f9daa5855382c
Merge "Fix Bad except clauses order"
Merge "Reserve 10 migrations for backports"
remove scary error message in tox

Found an interesting cantrip in the devstack tox.ini that gets rid of
the scary can't find bash error message at the beginning of test
runs. Reducing non error looking error things make it easier to see
real errors.

Change-Id: I4e1b826626063bf8d5a15531f5768f9ce0eea6a5
Merge "remove scary error message in tox"
Merge "move integrated api client to requests library"