get hostname only once, when class loads

in production, we’re getting out of memory errors when making the
system call which attempts to fork a new process. This change gets the
hostname only once, as the class loads.
Merge pull request #7 from cloudsponge/master

Resolves Out Of Memory errors
Update README
Bump version to '0.1.0'
Merge pull request #6 from simonini/master

For Rails 4.1 and fix readme.
Update README
Bump version to 0.2.0
Update Gemfile.lock
send mail when error