Bug 17504: Make the installer show the right dmbs help if wrong permissions

Bug 17504: Make the installer show the right dmbs help if wrong permissions

This patch changes the installer template for step 2 (DB rights check)
so it correctly displays MySQL-related message.
The previous code was doing the wrong comparisson, thus yielding
PostgreSQL documentation.

To test:
- Run:
  $ sudo koha-mysql kohadev
  > DROP DATABASE koha_kohadev ; CREATE DATABASE koha_kohadev;
  > REVOKE INSERT ON koha_kohadev.* FROM 'koha_kohadev'@'localhost';
  > FLUSH PRIVILEGES; \q
- Run the webinstaller through step 2
=> FAIL: You get the message in the attached screenshot
- Apply the patch, reload
=> SUCCESS: You are displayed a different warning message, with a link
to up-to-date MySQL docs on GRANT
- Fix permissions for the user:
  $ sudo koha-mysql kohadev
  > GRANT ALL PRIVILEGES on koha_kohadev.* TO 'koha_kohadev'@'localhost';
  > FLUSH PRIVILEGES; \q
- Reload
=> SUCCESS: All checks are correct and you can move on
- Sign off :-D

Signed-off-by: Josef Moravec <josef.moravec@gmail.com>
Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>