Add support for <cinder type-list> and <cinder create --volume-type>

Added support for volume types
I understand now that you are asking us to handle new line characters that are within a json string value. The reason it works in the above case is that it is using the triple quoted string and the python interpreter parses these differently.  We are reading the content of the file which is a json string.  When we read from a file, we get a string stored in a variable which does not have the triple quote advantage.  Prefixing and affixing triple quotes to the variable did not help.  For us to determine whether the new line is inside the json string or outside the json string would take regex to detect and escape those cases which is done by simplejson but not by json library.   Maybe my knowledge in python is limited with respect to this.  Any suggestions?  Removing the two lines requested breaks json.loads.