Merge pull request #2 from preaction/check-path-string

path argument must not be ref or will segfault
Make note of Doug Bell's fix for the constructor
Bump version to 0.12
Merge pull request #3 from preaction/constructor-options

Constructor options
allow single argument (path) to constructor

Now the simplest case is just Mac::FSEvents->new( $path );
document new constructor options

Document the new non-ref and single path argument variations of the
constructor.