Feat/2 step opt

[matiu]

Optimizes 2-step balance:

1- prevent counting addresses if wallet was already determined big enough
2- prevent the "second step" if it was performed in less that 1hr ago and it had no result
3- adds tests to 'address activation' by BCmonitor
4- better fetching/query for 'active' addresses

[coveralls]

Coverage increased (+0.06%) to 83.348% when pulling 002f9c7 on feat/2-step-opt into 7a12b17 on master.

[coveralls]

Coverage decreased (-0.1%) to 83.168% when pulling 2d46dca on feat/2-step-opt into 7a12b17 on master.

[coveralls]

Coverage decreased (-0.1%) to 83.168% when pulling 2d46dca on feat/2-step-opt into 7a12b17 on master.

[cmgustavo]

LGTM. Test OK (Create, Re-create, Import, Send, Receive)

[coveralls]

Coverage decreased (-0.1%) to 83.175% when pulling 0b6e577 on feat/2-step-opt into 7a12b17 on master.

[coveralls]

Coverage decreased (-0.1%) to 83.186% when pulling b8c52a8 on feat/2-step-opt into 7a12b17 on master.

[cmgustavo]

Ack