Use Config nesting in `SapphireTest::useTestTheme()`

Using the Config nesting functionality to restore variables
BUG Fix PDOConnector issues
Travis support for PDO
ATTR_EMULATE_PREPARES = false breaks some test cases
Enable username sans password
Remove unnecessary semicolons delimiting queries
Merge pull request #3353 from tractorcow/pulls/3.2/fix-pdo

BUG Fix PDOConnector issues
API Use "number" HTML5 type for NumericField by default
Merge pull request #3361 from halkyon/number_type_numericfield

API Use "number" HTML5 type for NumericField by default
Merge pull request #3094 from dhensby/patch-3

Use Config nesting in `SapphireTest::useTestTheme()`