added task logger and r errors manages inside the task
Merge branch 'master' of github.com:openforis/calc into steptest

Conflicts:
	calc-core/src/main/java/org/openforis/calc/r/REnvironment.java
	calc-core/src/main/java/org/openforis/calc/r/RScript.java
	calc-webapp/src/main/webapp/css/calc.css
Code clean