More informative error handling when connection string is ill-formed

[hokster7]

I tried to hack up database access quickly by writing something like this CoffeeScript, expecting the package to guide me through informative errors:

app.use orm.express '',
  define: (db) ->
    return

, I run into this:

TypeError: Cannot call method 'replace' of undefined
    at Object.exports.connect (<project>/node_modules/orm/lib/ORM.js:58:29)
    at Object.module.exports (<project>/node_modules/orm/lib/Express.js:9:6)
    at Object.exports.express (<project>/node_modules/orm/lib/ORM.js:20:30)

node-orm2 just blindly assumes that there is a colon to be matched in the connection string in ORM.js:58:

var proto  = opts.protocol.replace(/:$/, '');

but in fact, we mustn't assume the connection is valid all the time.

[dresende]

I'll change the db.connect to be more error prone and avoid throwing unexpected errors.

[dresende]

I think these 2 errors already give you something. If you think there are more checks that should be done, feel free to reopen.