Run unit tests against MySQL

- Creates a new tox environment for testing against mysql
- Adds a script set-test-env-mysql.sh to set up mysql
- Adds a new file `functions.sh` for common shell functions
- Creates a new DB manager for tests
- Adds a new scenario for mysql in the MixinTestsWithBackendScenarios

Related to blueprint sql-unit-tests-on-real-backend
Co-Authored-By: Ala Rezmerita <ala.rezmerita@cloudwatt.com>

Change-Id: I2c7378c79b1a0bffae5b2489b04c60e509f62f85

tox.ini

@@ -1,7 +1,7 @@
 [tox]
 minversion = 1.6
 skipsdist = True
-envlist = py26,py27,py33,pep8
+envlist = py26,py27,py27-mysql,py33,pep8
 
 [testenv]
 deps = -r{toxinidir}/requirements.txt
@@ -12,10 +12,14 @@ setenv = VIRTUAL_ENV={envdir}
          EVENTLET_NO_GREENDNS=yes
          PYTHONHASHSEED=0
 commands =
-   bash -x {toxinidir}/setup-test-env.sh python setup.py testr --slowest --testr-args="{posargs}"
+   bash -x {toxinidir}/setup-test-env-mongodb.sh python setup.py testr --slowest --testr-args="{posargs}"
 downloadcache = {toxworkdir}/_download
 whitelist_externals = bash
 
+[testenv:py27-mysql]
+commands =
+   bash -x {toxinidir}/setup-test-env-mysql.sh python setup.py testr --slowest --testr-args="{posargs}"
+
 [testenv:py33]
 deps = -r{toxinidir}/requirements-py3.txt
        -r{toxinidir}/test-requirements-py3.txt