Refactor tox a bit

requirements-precise.txt

@@ -1,6 +0,0 @@
-PyYAML==3.10
-simplejson==2.3.2
-netifaces==0.8
-netaddr==0.7.10
-Jinja2==2.6
-six==1.1.0

requirements.txt

@@ -1,4 +1,4 @@
-PyYAML==3.10
+PyYAML>=3.10
 simplejson==3.3.1
 netifaces==0.8
 netaddr==0.7.10

tox.ini

@@ -1,6 +1,6 @@
 [tox]
 # Default to current LTS
-envlist = pep8,py27-trusty
+envlist = pep8,py27
 skipsdist = True
 
 [testenv]
@@ -11,19 +11,14 @@ install_command =
   pip install --allow-unverified python-apt {opts} {packages}
 commands = ostestr {posargs}
 
-[testenv:py27-precise]
+[testenv:py27]
 basepython = python2.7
-deps = -r{toxinidir}/requirements-precise.txt
-       -r{toxinidir}/test-requirements.txt
-
-[testenv:py27-trusty]
-basepython = python2.7
-deps = -r{toxinidir}/requirements-trusty.txt
+deps = -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
 
 [testenv:pep8]
 basepython = python2.7
-deps = -r{toxinidir}/requirements-trusty.txt
+deps = -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
 commands = flake8 {posargs} hooks unit_tests tests
            charm proof