Require rake ~> 10.0.
Refactored the Ronin::SQL into a more ARel like DSL, with method chaining.

* Added Ronin::SQL::BinaryExpr.
* Added Ronin::SQL::Clause.
* Added Ronin::SQL::Clauses.
* Added Ronin::SQL::Emitter.
* Added Ronin::SQL::Field.
* Added Ronin::SQL::Fields.
* Added Ronin::SQL::Function.
* Added Ronin::SQL::Functions.
* Added Ronin::SQL::Injection.
* Added Ronin::SQL::Operators.
* Added Ronin::SQL::Program.
* Added Ronin::SQL::Statement.
* Added Ronin::SQL::UnaryExpr.
Raise NoMethodError and convert the field name to a String.
Added specs for Field.
Deleted the old Fragment specs.
Updated the SQL helper method specs.
Added new specs for SQL::Function.
Always convert the Field name to a String.
Call super from method_missing.
Added specs for SQL::Fields.
Include Statements into Clause for the UNION clause.
Added specs for Clauses.
Added specs for Clause.
Added the IN operator method.
Added specs for SQL::Functions.
Added a PLACE_HOLDERS hash.
Style.
Fixed circular require issues.
Handle emitting nil.
Default :escape to :column.