Update $drivers to contain Backhole

Needed for StashBundle to be able to use this as a fallback.
Merge pull request #65 from andrerom/patch-1

Update $drivers to contain BackHole
FileSystem driver now tries to create cache folder before throwing InvalidArgumentException
Removed dump to /dev/null for testing purposes.
Updated travis startup to use preinstalled extensions
Corrected php extension configuration
Remove tests folder from composer.json
[Fix] Fixed PHPDoc for code completion

In IDE function getItem return Stash\Item, must return \Stash\Item.
Fix in memcache.php
Updated APC configuration for CLI tests

Since the tests need to run through the CLI, APC needs to be enabled
there.
Merge pull request #72 from tedivm/travis_test

Updated Travis CI tests to work with new PHP Extension handling.
Merge pull request #70 from dementyev-alexey/master

[FIX] Pool class PHPDoc fix for code completion
Merge pull request #69 from Baachi/fix-composer

Remove tests folder from composer.json
Merge pull request #66 from lolautruche/filesystem_dir_creation

FileSystem driver now tries to create cache folder before throwing InvalidArgumentException
Merge pull request #71 from pedroresende/array_error

Fix in memcache.php
Revert "Merge pull request #71 from pedroresende/array_error"

This reverts commit df441ca1d6fbd41acc170bf71f217b5f85298c8e, reversing
changes made to 1606a2b768da071b97a001434a4d5d341bf975d9.
Updated the Pear package file.
Updated FileSystem and Sqlite handlers to more accurately check file permissions and report on error states.

Fixed the Apc driver to correctly report the handler as unavailable when running in CLI environment with apc.enable_cli = Off.
Fixed typo
Merge pull request #74 from pborreli/patch-1

Fixed typo- this typo results in some potentially unexpected behavior with the Session handler, as results are not always returned in the right manner.