Add triggerError and slientError method to Result class
Add build status
Throw InvalidValueTypeException if the type does not match constraint
Make checkTypeConstraint method returns error instead of throwing exception
Throw DatabaseException at correct places.
Clean up unused code
Reduce variable
use reportSuccess / reportError since we'd like to save the last result
Fix tests for php(s) or hhvm without pgsql extension
more test versions
update .travis ci config
pdo_ prefix
SchemaInterface type constraint
type constraint PDO
SQLBuilder\Driver type constaint
QueryDriver class type constraint
Add PDO type constraint
Add ColumnAccessorInterface
Add getValidValues to ColumnDeclare
Add asRuntimeColumn method to ColumnDeclare

This is for reusing the accessor methods from RuntimeColumn.

In the future we might need a base class to share the methods between
the two.