This is a patch to commons.lang to add the following two methods
public static String join(Object array, char separator)
public static String join(Iterator iterator, char separator)
They're equal to the ..., String separator) methods but take
a char as second parameter.
I also took a look at the other join methods and enhanced them for the
separator == null case.
The test case for join has been extended for test cases of the new
methods, tests for the null separator and some test for joining
an empty array / collection object.