added toString() method for CaseInsensitiveMultiMap (version for 2.x)

Signed-off-by: Alex <alexlehm@gmail.com>
changed iterator to for, added spaces

Signed-off-by: Alex <alexlehm@gmail.com>
Merge pull request #944 from alexlehm/bz430965_v2.x

added toString() method for CaseInsensitiveMultiMap (version for 2.x)
Small change to CaseInsensitiveMultiMap.toString()