Update tox.ini to use skipsdist/develop

No sense in making tarballs every time.

Change-Id: I6aaeb9b78922a7a39d6e7d7cbe0a595a07f5808c

tox.ini

@@ -1,5 +1,6 @@
 [tox]
 minversion = 1.6
+skipsdist = True
 envlist = py26,py27,pep8
 
 [testenv]
@@ -7,6 +8,7 @@ setenv = VIRTUAL_ENV={envdir}
          LANG=en_US.UTF-8
          LANGUAGE=en_US:en
          LC_ALL=C
+usedevelop = True
 install_command = pip install {opts} {packages}
 deps = -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
@@ -31,4 +33,4 @@ commands = {posargs}
 [flake8]
 exclude = .venv,.tox,dist,doc,*.egg
 show-source = true
-ignore = E123,E125
+ignore = E123,E125