[Tests] Cover startmasternode all option

Adds a method to start multiple MNs with a single command, adding code
coverage to the more 'heavy-lifter' portion of the startmasternode
command.

test/functional/test_framework/test_framework.py

@@ -1035,6 +1035,14 @@ def controller_start_masternode(self, mnOwner, masternodeAlias):
         time.sleep(1)
 
 
+    def controller_start_masternodes(self, mnOwner, aliases=[]):
+        ret = mnOwner.startmasternode(set="all", lock_wallet=False, reload_conf=True)
+        for i in range(len(aliases)):
+            assert_equal(ret["detail"][i]["alias"], aliases[i])
+            assert_equal(ret["detail"][i]["result"], "success")
+        time.sleep(1)
+
+
     def send_pings(self, mnodes):
         for node in mnodes:
             try:

test/functional/tiertwo_governance_reorg.py

@@ -83,8 +83,7 @@ def run_test(self):
         mn2.initmasternode(self.mnTwoPrivkey, "127.0.0.1:"+str(remoteTwoPort))
         self.stake_and_ping(self.minerAPos, 1, [])
         self.wait_until_mnsync_finished()
-        self.controller_start_masternode(minerA, self.masternodeOneAlias)
-        self.controller_start_masternode(minerA, self.masternodeTwoAlias)
+        self.controller_start_masternodes(minerA, [self.masternodeOneAlias, self.masternodeTwoAlias])
         self.wait_until_mn_preenabled(self.mnOneCollateral.hash, 40)
         self.wait_until_mn_preenabled(self.mnOneCollateral.hash, 40)
         self.send_3_pings([mn1, mn2])