Alternative topic separators should be supported in Apollo, as in ActiveMQ

When using a character other than a period as a topic separator (.), Apollo throws the following exception:

 
org.apache.activemq.apollo.util.path.PathParser$PathException: Invalid destination path part: 'event/abc', it does not match regex: [a-zA-Z0-9\_\-\%\~]+

In the example, we're using /topic/event/abc as a topic. In PathParser.java, line 47 determines that path_seperator = new AsciiBuffer("."). Thus, Apollo incorrectly tokenizes the topic and so event/abc fails the regular expression on line 48 of the same file.

In short, it should be possible to specify what the topic separator is, or (even better) detect when a different character is being used as a delimiter.