Deprecations in 0.3.0

[dnicolodi]

Tracking issue for deprecations to be introduced in version 0.3.0.

Approximately in order of importance, or in order of how annoying the features are to maintain:

• expressions in the FROM clause, see also #34
• double quoted strings
• beanquery.query.run_query() and the beanquery.query module,
• year, month, day columns
• year(), month(), day() functions
• one argument version of parse_date()
• safediv() function