testing to log every query chain
checking where the code for computing the sound_rank fails in the test server.
removing the online processing of session information in the clickthrough tracking. click session tracking will be done offline.
- log a user query, sounds in page, and page number
- log which sound user previewed/sound-downloaded/pack-downloaded
adding do_log to the context of sound.html node to enable preview link intercepting and preview tracking. Similar to what is happening wrt previewing in search results page.
changing "anonymous_session_key" in the session information to "searchtime_session_key". the term was misleading. the main purpose is to be able to track the user's search and click actions.
Merge branch 'feature-clickthroughLogging' of https://github.com/MTG/freesound into feature-clickthroughLogging

Conflicts:
	search/views.py
	sounds/views.py