(TOX) Created .tox file and tests/ folder

Created base .tox file and moved everything test-related to tests/ folder.
(TOX) Finalized Tox transition

Tests are run with nose instead of pytest since it was previously used for writing tests;
Moved tests/ to cmsplugin_feed/tests/;
Changed paths and imports in tests/ so that everything works properly;
Removed unnecessary files;
Updated .gitignore file.
(tox) Review changes

Renamed branch;
Added py.test to tox and resolved name clashes;
Changed tests that used nose module to generic unittest module;
Updated .gitignore
(tox) Some fixes

Added changedir for tox commands and moved results xml file accordingly.
(tox) Tox nose env runs properly now
Merge pull request #4 from pbs/tox

Integrated Tox