Redundant primary key in `AcHostModelSchema`

[Nader Hadji Ghanbari]

After upgrading to ac-play-scala % "0.4.1", the startup ddl fails with the following exception:

play.api.UnexpectedException: Unexpected exception[JdbcSQLException: Attempt to define a second primary key; SQL statement: alter table "ac_host" add constraint "pk_ac_host" primary key("id") [90017-175]] at play.core.ReloadableApplication$$anonfun$get$1$$anonfun$apply$1$$anonfun$1.apply(ApplicationProvider.scala:166) ~[play_2.11-2.3.4.jar:2.3.4] at play.core.ReloadableApplication$$anonfun$get$1$$anonfun$apply$1$$anonfun$1.apply(ApplicationProvider.scala:130) ~[play_2.11-2.3.4.jar:2.3.4] at scala.Option.map(Option.scala:145) ~[scala-library-2.11.2.jar:na] at play.core.ReloadableApplication$$anonfun$get$1$$anonfun$apply$1.apply(ApplicationProvider.scala:130) ~[play_2.11-2.3.4.jar:2.3.4] at play.core.ReloadableApplication$$anonfun$get$1$$anonfun$apply$1.apply(ApplicationProvider.scala:128) ~[play_2.11-2.3.4.jar:2.3.4] Caused by: org.h2.jdbc.JdbcSQLException: Attempt to define a second primary key; SQL statement: alter table "ac_host" add constraint "pk_ac_host" primary key("id") [90017-175] at org.h2.message.DbException.getJdbcSQLException(DbException.java:332) ~[h2-1.3.175.jar:1.3.175] at org.h2.message.DbException.get(DbException.java:172) ~[h2-1.3.175.jar:1.3.175] at org.h2.message.DbException.get(DbException.java:149) ~[h2-1.3.175.jar:1.3.175] at org.h2.message.DbException.get(DbException.java:138) ~[h2-1.3.175.jar:1.3.175] at org.h2.command.ddl.AlterTableAddConstraint.tryUpdate(AlterTableAddConstraint.java:110) ~[h2-1.3.175.jar:1.3.175]