Update to handle minecraft 1.7.+ log format and location

Updated timestamp parsing and regex for 1.7.+ log format
Updated default log path to match new location for 1.7.+
This should fix https://github.com/marcuswhybrow/minecraft-server-manager/issues/159 and possibly other issues, but may break compatibility with older versions. A workaround could be to re-introduce the date into the regex and make it optional, together with the colon and the brackets.