Better API support for querying #27
Description
It would be nice to add some better API support for querying the process status.
For example, if there is no extant pidfile, the .check() method throws an IOError due to lack of write access. I suppose this could be interpreted as "file does not exist", but it's not very clear.
It would also be nice to be able to get access to the numeric pid if it exists. As it is now, if a process is already running, calling .check() throws an exception. The error message does contain the pid of the running process, but unless I'm missing something, there's no way to access it without parsing it out of the error message.