Add 'isConnected' function to menash

[Shahar-Y]

Currently, it seems there is no way to know whether or not there already is a connection to rabbit, which complicates the users of the package.
An isConnected function could fix that.

[Randomize163]

Hi Shahar,

You could check menash.isReady field to check if menash is connected until we add a support for menash.isConnected()

Thanks,
Alexander