Cleaned up build.xml.
Cleaned up build.xml.

Simplified the Javadoc target by replacing many of the variables from
the NetBeans target with logical constants. Removed dependency on
the properties file in the root wpilib directory, as this only set two
properties and is only created by the FIRST plugins. Added comments.

RVRProgramming/Diablo2015,RVR-Programming/Diablo2015