expr: scalar date/datetime coercion
expr: basic unsafe exprify implementation
server: Selection API
py2.6 compatibility, dict comprehension
fix typo in docstring
Cleaner SQL for projections using .with_only_columns
Test datetime serialization
py3: remove \s0\d like 01
serve: use dynd for json formatting

better date/datetime support
expr: safer exprify
future imports
add more illegal terms to exprify

http://lybniz2.sourceforge.net/safeeval.html
http://nedbatchelder.com/blog/201206/eval_really_is_dangerous.html
more safety around exprify
expr: rename coerce->scalar_coerce to avoid conflict

Also match coerce API
expr: tests and more functionality for scalar_coerce
expr: raise error on lossy datetime conversion
Merge pull request #353 from mrocklin/scalar-coercion

Scalar coercion - Server selection