Expand implicit $and operator at top level

This is to start preparing for supporting nested $and and $or clauses.
Create and use query execution tree for single level AND queries
Support nested AND fragments in building SQL tree

Not tested support for executing yet.
Implement $or operator in queries
Merge pull request #1 from cloudant/nested-queries

Nested queries
Add licence headers where missing
Correct a misleading turn of phrase
Xcode 6 requires Specta 0.3.x
Try removing xctool from Travis run
Try cleaning up travis output
Update README.md
Update README.md
Update README.md
Update README.md
Added CDTQLogging.h

Added CDTQLogging.h file which contains macros to use
CocoaLumberJack logging framework. The log statements are
name spaced with the prefix CDTQ
Add error messages to log
Add Change Log Level macro
Add document describing logging for CDQ
Updates to logging doc
Remove comment