add voting tests

[oxarbitrage]

Testcase for #1191

It is a bit too big as i had to take control of the network by adding my witnesses and my committee. This is a process already done in smartcoin_tests. We need to improve it a bit for general use IMO and add it to fixture maybe.

After that is done, the real test action is done when checking votes at when tracking is enabled:
BOOST_CHECK_EQUAL(witness1_object->total_votes, 111);
and when it is disabled:
BOOST_CHECK_EQUAL(witness1_object->total_votes, 0);

Same is done for the committee members.

[abitmore]

Looks good. Thanks!

• the hack in database_fixture.cpp is debatable,
• agree with you about the common code,

but we can improve them later.

I've merged #1191 and changed base of this PR to develop.

Travis-CI timed out. I've restarted it. Will merge later.