Frontend DPU replace method updated
DPU gets unique jar-file name during creation, DPU create process
updated
Pre/Post DPU executors are ordered, Context is prepared in executor.
Merge branch 'master' of https://github.com/mff-uk/intlib.git

Conflicts:
	frontend/src/main/java/cz/cuni/xrg/intlib/frontend/gui/components/DPUCreate.java
DirectoryWatcer replaced by FileNotifier, fixed bug with DPU delete
Backend logback configuration update, should preserve logs in files for
three days now
Nonfunctional change: class visibility restricted