Add option to skip exception types for logging.

add blacklisting for logging exceptions

add test for skipping exception logging, and fix typo and cs

add example to docblock in core.php for skipLog

remove app_error.php skips, those are no longer used in 2.x

use assertContains instead of assertRegExp

check for instanceof, instead of matching names
Merge pull request #1186 from ceeram/2.4-blacklist

2.4 blacklist