Merge pull request #4 from greydot/master

This time it works
hsyslog.cabal: bump major release version because of API change
System/Posix/Syslog.hsc: minor cosmetic change
Add a doctest test suite.
Greatly improved the Haddock documentation (and added doctests).
Remove the 'useSyslog' function. It's purpose is unclear to me know:
calling 'withSyslog' is just as easy, this function doesn't add any
value.
Fix comments