Two bug fixes for sqlite3 database connector

[dm-coding]

1. In the first instance, an invalid database configuration can sometimes result in a failure to connect to the SQLite database without an error. As no error is caught by CakePhP, PhP itself throws a fatal error on line 221 as no $connection object exists. This bug fix forces the _execute() function to check that the database is in fact connected - if not, CakePhP gracefully throws a helpful error message to the user.

Reported here: http://stackoverflow.com/questions/4779007/cakephp-and-sqlite-fatal-error-call-to-a-member-function-query-on-a-non-obje, here: http://stackoverflow.com/questions/7107996/fatal-error-call-to-a-member-function-query-on-a-non-object-in-var-www-likes, and here: http://stackoverflow.com/questions/7572091/error-while-trying-to-connect-to-sqlite3-database-from-cakephp
To reproduce: set $config['connect'] to an invalid value.

2. In the second instance, the sqlite driver ignores SQL views. Changing the SQL query to read "SELECT name FROM sqlite_master WHERE type='table' OR type='view'" where it previously read just "type='table'" fixes this problem.

All the best,

Daniel

[AD7six]

A test case is easier to read than an inline comment, and would help prevent a future regression.

[AD7six]

In the first instance, an invalid database configuration can sometimes result in a failure to connect to the SQLite database without an error.

Is this point still relevant? if the config is invalid what should happen is to fail early so the developer can fix their config.

I've created a seperate 1 line PR (#100) for the second point.