fix(subscription-multipexing) allows client to subscribe to multiple similar topics closes #19

- adds new test for this `test_mqtt_multiple_peers_regex.c'
- corrects some comments
- updates GNUNET_REGEX structs
- adds some logging
- adds proper regex usage, i.e. go for exact match not prefix match
chore(test-topics) gives each test a unique topic prefix

- prefixes are `some%d' where d is the order the test cases appear in the Makefile.am (starting at 1)
Merge pull request #21 from vsaw/fix/subscription-multiplexing

fix(subscription-multipexing) allows client to subscribe to multiple sim...