Catch "URLError: No route to host" while fetching and move to next url.

 * Before, if blockfinder was unable to resolve a hostname, it would barf up
   the unhandled error in the terminal and exit. Instead, we should at least
   catch the error, display a message to the user that there was a problem
   caching whichever URL failed, and move on to the next URL. We might want to
   retry the url instead, but my tests of this patch on my local network
   (where DNS is highly tampered with and censored) show the following
   results (instead of just crashing):

∃!isisⒶwintermute:blockfinder(develop *+=) ∴ blockfinder -i
Downloading RIR files...
Fetching 3207 kilobytes
[=============================================================>] 365.58 K/s
Fetching 0 kilobytes
[=============================================================>] 0.00 K/s
An error occurrred while attempting to cache file from:
        ftp://ftp.ripe.net/ripe/stats/delegated-ripencc-latest
        <urlopen error ftp error: [Errno 113] No route to host>
An error occurrred while attempting to cache file from:
        ftp://ftp.ripe.net/ripe/stats/delegated-ripencc-latest.md5
        <urlopen error ftp error: [Errno 113] No route to host>
Fetching 171 kilobytes
[=============================================================>] 67.89 K/s
[...]
Verifying RIR files...
Importing RIR files...
∃!isisⒶwintermute:blockfinder(develop *+=) ∴
Fix SyntaxError due to Python2.x-styled print statement.
Merge pull request #67 from isislovecruft/testing/develop

Testing/develop from the epic isislovecruft