issue #174: fixed key validation
do not rely that much on error message

Conflicts:
	tests/TransactionTest.php
Merge branch 'master' of https://github.com/triAGENS/ArangoDB-PHP
updated domain
ignore certificate
Make samples work cut'n'pasteable
fixed examples

Conflicts:
	README.md
fixed examples
issue #173
Merge branch '2.2' of https://github.com/triAGENS/ArangoDB-PHP into 2.2