Step 7 complete. Added a function similar to the previous delimiter function, but adds a delimiter of any length to the string of delimiters.
Also added a if-statement to the sum function, to check whether it's adding an empty character.
Also had to re-order the if-else statements, in the add function.
Two test cases added to verify the results.
Step 8 almost complete.
Some problems regarding reserved characters in RegEx.
Merge branch 'master' of github.com:gislirafn/String-Calculator

Conflicts:
	classes/is/ru/stringcalculator/Calculator.class
	classes/is/ru/stringcalculator/CalculatorTest.class
	src/main/java/is/ru/stringcalculator/.Calculator.java.swp
	src/main/java/is/ru/stringcalculator/Calculator.java
	src/test/java/is/ru/stringcalculator/CalculatorTest.java