Merge pull request #8 from alexislg2/cbOnDeleted

add callback call that was missing to the deleteMessage function
fix

Calling `.close()` on a closed port, trow an exception. This happens when you try to open a non existent port. This patch fixes.
Update modem.js

Call callback if exists and on error!
Update modem.js

fix null pointer exception.
Update modem.js

returning string instead of error
Update modem.js

changed returning error string
Fixed timeout on commands

Fixed timeout on commands
Update modem.js

Refixed throw
fix callbacks
Merge branch 'master' of github.com:brugnara/modem
Update README.md
Update README.md
Merge branch 'master' of https://github.com/brugnara/modem into brugnara-master

Conflicts:
	README.md
	package.json