Add divide operation. Se modifica el fichero Calculator.java

Change-Id: I303e81e84b6a64c2b9f03bfb5c386e7b6855f657
Merge remote-tracking branch 'origin/master'

Conflicts:
	org.eclipse.example.calc/src/org/eclipse/example/calc/internal/operations/Divide.java

Change-Id: Ie411ff7405d17376d07ea80864ce8d3cc4f5f888