Fix a bug related to earlier refactoring of PackageVariants to contain PackageRequests instead of string requests.
Code cleanup and documentation improvement
Certain env variables have special meaning to python and rez and should affect the current running python session when using a Python command interpreter.
Rename rez_release to release.
Rename rez_filesys to filesys.
Rename rez_parse_request to parse_request.
Rename rez_memcached to memcached.
Rename rez_util to util.
Rename rez_config to config.
Rename rez_exceptions to exceptions.
remove stray print statement
package rename bugfix