This adds a new keyword argument to the init method, `allow_fail`. When
set to True (default is False) then a failure to configure is not an
error, and output is still returned. This can be useful for cases where
we expect initialization to fail, and want to check the output.
There are two problems with having this in the try/except block. The
first is that both of the if statements will raise, and the except
statement cathces `Exception`, so it catches these two cases, prints a
message that we either don't want or already printed, then re-raises.
Dylan Baker
Eli Schwartz
Xavier Claessens