Six is a runtime requirement not a test req

Six needs to be installed when python-jenkins is installed. By default
test-requirements are only installed when running tests. Six was listed
as a test-requirement so it was not installed when pip installing
python-jenkins. Make six a regular requirement so that it is installed
properly every time.

Change-Id: I2b7cb7e967b20ee0e06fe4c665f08c5932e524f2

requirements.txt

@@ -0,0 +1 @@
+six

test-requirements.txt

@@ -2,7 +2,6 @@ coverage>=3.6
 discover
 hacking>=0.5.6,<0.8
 mock
-six
 #unittest2
 python-subunit
 sphinx>=1.1.2,<1.2

tox.ini

@@ -7,7 +7,8 @@ envlist = pep8, py26, py27, pypy, py33, py34
 setenv VIRTUAL_ENV={envdir}
 usedevelop = True
 install_command = pip install {opts} {packages}
-deps = -r{toxinidir}/test-requirements.txt
+deps = -r{toxinidir}/requirements.txt
+       -r{toxinidir}/test-requirements.txt
 commands = python setup.py testr --slowest --testr-args='{posargs}'
 
 [testenv:cover]
@@ -16,7 +17,8 @@ commands =
     coverage report --show-missing
 
 [testenv:py26]
-deps = -r{toxinidir}/test-requirements.txt
+deps = -r{toxinidir}/requirements.txt
+       -r{toxinidir}/test-requirements.txt
        unittest2
 
 [tox:jenkins]