Fix failing unit tests in java 8

The user.timezone property for the surefire plugin must match
the setting via argLine. The pom was inheriting the property from
airbase set to UTC, but argLine was set to Asia/Katmandu.

As far as I can tell, the surefire plugin executes the following steps:
- create a VM using the argLine arguments
- call setProperty for each systemPropertyVariable
- run the tests

Unlike Java 7, calling System.setProperty for user.timezone in Java 8 after the VM is initialized
has no effect. See d2fee8d93952054883bf94a65576cead632314cf for additional details