Provide more debug info in verbose mode
Don't create new files by default

Most of the time editing a new file is not desired: if an existing test
file cannot be found, it's more likely the test switcher configuration
is incorrect than that the user wants to create a new file.

Let the user explicitly state that they want a new test file by adding a
! to the command, e.g. :SwitchCodeAndTest!
Ignore .pyc files