Integrating Bing Search API and Google Custom Search API
multiple requests and unit tests added
merging develop into feature/bing_google_search
chg: Added __init__.py to bing directory, making it a package to python
chg: added test-run command for bing search to tox.ini
chg: added lxml dependency to tox and nosetest command for google custom search. That fails right now due to __init__/python 3 problem
ported to Python 3