Fixed some errors

## Fix 1:
when requesting the score of the non-default-table, the server answered, that the signature was wrong

## Fix 2:
CNIAngel wrote:
"Has anyone had trouble with checking if the user has achieved a trophy or not?
I'm using the latest version of the .jar file and I know the trophy is achieved but the method isAchieved() always returns false.
Any insight as to why it's not working properly is appreciated."
http://gamejolt.com/community/forums/topics/java-api/239/?forum_topic_post_page=3
## Fix 3:
GIRakaCHEEZER wrote:
getTrophies is bugged.  You get a NullPointer exception if you try to use it with no trophies achieved (happens at line 994 in GameJoltAPI.java, since t can be null there).
http://gamejolt.com/community/forums/topics/java-api/239/?forum_topic_post_page=3