Add Connect and Disconnect mojos

With this PR, it is now possible to add external IP in the global configuration : for example 
<ips>
    <ip>127.0.0.1:555</ip>
</ips>

This list of IPs will be added automatically to the list of devices. 
Before running any maven goal, if you have external IPs, we should run mvn android:connect. 

The andoird:disconnect goal will disconnect all the IPs we have configured in the pom.xml. 

Manu