Fixed undefined variable - closes #13

By passing an undefined variable into bglib, the command packet builder was passing an undefined Buffer into Buffer.concat() which got treated as a <Buffer 00 >. This is coincidentally the correct value for addressType when connecting to a device with a public address, however iOS devices and the FitBit Flex use a random address, which requires a value of 1, rather than 0, in that parameter. This change ensures that the correct value is propagated down to bglib when the packet is created.

@johnnyman727