improvements

[till]

Hey Brian,

this pull contains the following:

• public Net_Gearman_Task::$server (assigned in Net_Gearman_Client::submitTask())
• a new test to cover Net_Gearman_Task::$handle and Net_Gearman_Task::$server
• use of type hints to enforce data types
  • possible BC break in Net_Gearman_Task::__construct()
• stripped trailing ?> from most files
• a couple CS fixes
• disabled the 012-*.phpt until we figure it out (please re-open that issue)

Let me know what you think.

Till