Add methods, make certain tests more robust, change Random.state to Random.state_abbr to avoid some kind of private name collision

Added the following methods:

* url: URL with random domain, subdomain, protocol (http or https), number of subdirectories, and filename extension.  Note that # of subdirs, protocol, and file extension can be fixed by the caller with an options hash.
* img_url: same as above, but with an image extension
* address_one_line: convenience method for creating a one line address (address_line_1, city, state_abbr, zipcode)

Also refactored test harness & a bunch of tests that were failing for me on Ubuntu 13.04/13.10, using rvm & ruby-1.9.3-p362.  I made them check for just alphanumeric pattern, rather than a specific string.