Marcel 1.1.0 no longer recognises bzip2 files by magic

[tomhughes]

Marcel 1.1.0 fails to identify bzip2 files by magic.

The problem stems from 6bf4d97 which actually stopped them wrongly matching as application/x-bzip but the new fixed application-x-bzip2 rule doesn't work because it's acctually a regular expression but marcel matches using string equality.

There are a number of other magic rules which appear to now be regular expressions and which therefore won't match correctly.