Target path for gradle builds is wrong for FindBugs

[SpOOnman]

Results in:

08:40:49.205 [main] WARN p.t.s.p.f.CollectorBugReporter - Analysis error File not found: filesystem:/media/truecrypt/jenkins/jobs/sputnik-gerrit/workspace/target/classes
08:40:49.210 [main] ERROR p.t.s.p.findbugs.FindBugsProcessor - FindBugs process error
java.io.IOException: No files to analyze could be opened
at edu.umd.cs.findbugs.FindBugs2.execute(FindBugs2.java:275) ~[findbugs-2.0.3.jar:na]
at pl.touk.sputnik.processor.findbugs.FindBugsProcessor.process(FindBugsProcessor.java:28) ~[sputnik-1.1.jar:na]
at pl.touk.sputnik.review.Engine.review(Engine.java:44) [sputnik-1.1.jar:na]
at pl.touk.sputnik.review.Engine.run(Engine.java:34) [sputnik-1.1.jar:na]
at pl.touk.sputnik.Main.main(Main.java:36) [sputnik-1.1.jar:na]

[SpOOnman]

This is now fixed with #70 .