Fix long javac commandline error

If the classpath is very long or the list of java files to compile is very
long, javac task will result in "Argument list too long" error.

This patch uses @argfiles [1] optinos to javac instead of commmand line
options.

[1] http://docs.oracle.com/javase/6/docs/technotes/tools/windows/javac.html
Merge pull request #983 from paraseba/long-javac-commandline

Fix long javac command line error