Fix the server tests

[AlexITC]

Some server tests are failing, they seem to be related to a text change which wasn't updated on the test files:

[info] - must reject bob due to wrong secret *** FAILED ***
[info]   java.lang.AssertionError: assertion failed: expected CommandRejected(The secret or the channel is incorrect), found CommandRejected(The secret or the room is incorrect)
[info]   at scala.Predef$.assert(Predef.scala:223)
[info]   at akka.testkit.TestKitBase.expectMsg_internal(TestKit.scala:403)
[info]   at akka.testkit.TestKitBase.expectMsg(TestKit.scala:379)
[info]   at akka.testkit.TestKitBase.expectMsg$(TestKit.scala:379)
[info]   at akka.testkit.TestKit.expectMsg(TestKit.scala:896)
[info]   at com.alexitc.chat.actors.PeerActorSpec.$anonfun$new$3(PeerActorSpec.scala:52)
[info]   at org.scalatest.OutcomeOf.outcomeOf(OutcomeOf.scala:85)
[info]   at org.scalatest.OutcomeOf.outcomeOf$(OutcomeOf.scala:83)
[info]   at org.scalatest.OutcomeOf$.outcomeOf(OutcomeOf.scala:104)
[info]   at org.scalatest.Transformer.apply(Transformer.scala:22)
[info]   ...
[INFO] [10/06/2019 16:32:19.335] [PeerActorSpec-akka.actor.default-dispatcher-3] [akka://PeerActorSpec/user/channel-handler] a peer with name=bob is trying to join room=test-channel
[INFO] [10/06/2019 16:32:19.335] [PeerActorSpec-akka.actor.default-dispatcher-3] [akka://PeerActorSpec/user/channel-handler] bob has joined test-channel
[info] - must allow bob to join
[INFO] [10/06/2019 16:32:19.336] [PeerActorSpec-akka.actor.default-dispatcher-3] [akka://PeerActorSpec/user/channel-handler] ActivePeers = 2, TotalPeers = 2, ActiveChannels = 1
[INFO] [10/06/2019 16:32:19.339] [PeerActorSpec-akka.actor.default-dispatcher-4] [akka://PeerActorSpec/user/channel-handler] Rejecting peer due to channel full, failed 1 times
[info] - must reject carlos due to channel being full *** FAILED ***
[info]   java.lang.AssertionError: assertion failed: expected CommandRejected(The channel is full, if you need bigger channels, write us to [email protected]), found CommandRejected(The room is full, if you need bigger rooms, write us to [email protected])
[info]   at scala.Predef$.assert(Predef.scala:223)
[info]   at akka.testkit.TestKitBase.expectMsg_internal(TestKit.scala:403)
[info]   at akka.testkit.TestKitBase.expectMsg(TestKit.scala:379)
[info]   at akka.testkit.TestKitBase.expectMsg$(TestKit.scala:379)
[info]   at akka.testkit.TestKit.expectMsg(TestKit.scala:896)
[info]   at com.alexitc.chat.actors.PeerActorSpec.$anonfun$new$5(PeerActorSpec.scala:62)
[info]   at org.scalatest.OutcomeOf.outcomeOf(OutcomeOf.scala:85)
[info]   at org.scalatest.OutcomeOf.outcomeOf$(OutcomeOf.scala:83)
[info]   at org.scalatest.OutcomeOf$.outcomeOf(OutcomeOf.scala:104)
[info]   at org.scalatest.Transformer.apply(Transformer.scala:22)
[info]   ...