Added a very preliminary version of the SQL cache proposal for Blaze.
Added some use cases for the design document for SQL cache
Relabeled sections as per Mark suggestions
Added an implementation outline section as Mark suggested.
Using deferred arrays syntax now
Merge branch 'master' of https://github.com/ContinuumIO/blaze into sql-cache
Added a complete example
New modifications based on discussions
Merge pull request #166 from FrancescAlted/sql-cache

A proposal for a simple SQL cache for Blaze.
Simplify dispatch to use one default ckernel dispatcher
Update the sql plugin for the dispatch changes
Update the scidb plugin for the dispatcher changes
Remove some old .gitignore entries
Fix to documentation in function.py