Handle multi-line better and cases where [Thread x] is not in the message

Hey Dan,

I've finally had time to test and update the code a litte. As you can see I've rearranged some of the regexes to support some cases that weren't handled properly before:
I now take each line of the log file and determine if it starts with: `2014-05-26 15:48:51,750 [5] INFO  Umbraco.Core.PluginManager - ` and then any text.
If that's the case, it's a new log entry. If not, it's a continuation of the previous entry so I append it to the last entry.

Some times the log message has `[Thread 12]` in it but sometimes not. When it exists, I grab the number of the thread and then remove `[Thread 12] ` (including space after it) from the message, when it doesn't exist, nothing happens of course.

This has been tested on about 15 sites with 25 logs in total now and it all seems to work perfectly.