Use repr() in string formatting over '%s'
Remove shebang on non-executable modules

Modules without a __main__ section don't need the shebang.
Follow good practice on string formatting

- Supply regular expressions as raw strings
- Use double quotes for language, single for regex and "symbol-like"
  strings (personal convention)
Give error message if start page omitted

urllib2's generic "HTTPError" message isn't terribly helpful (it doesn't
provide the URL as part of the message).

Handle the very possible case that a project start page doesn't exist:

- The label may not be created yet
- The label may be misspelled
- Label names may have taken a new format (necessitating code changes)