Changes

Major: The checkBucket() function was changed to use boto to check for buckets instead of GET'ing the page out on the web. This is better for several reasons:
- Buckets that are not open to the public, but are listable or are only open to authenticated users are now properly found
- Regions are no longer needed
Due to the change to use boto, AWS credentials are nearly required. The tool will still run without them, but results will be incredibly inaccurate. Users will receive a warning if credentials are not found.
The buckets.txt file now contains only bucket names instead of bucket:region
The screen output now says whether or not the bucket was found. The concept of 'open' vs 'closed' buckets no longer exists. This may change in the future.
The newly added checkBucketWithoutCreds will now issue a maximum of 2 requests to check if a bucket exists. This helps ease the issue of 503's being returned intermittently.
When dumping a bucket, the user can see that it's being dumped but doesn't get the ugly output. This is to allow the user to still cancel with Ctrl+C. A dumping progress feature will most likely be implemented in the future.
If a bucket doesn't allow listing of it's contents, the size will be "AccessDenied" or "AllAccessDisabled".

Features

Added: getAcl() to try to get the ACLs associated with found buckets. They're currently only output to the screen.
Removed: The --default-region argument. The new way of checking if buckets exist doesn't need the bucket's region and neither do any of the other functions. We're region-free now baby
Added: The --version argument. Pretty self-explanatory
Removed: The --include-closed argument. Now that the tool is more self-aware of the permissions on a bucket, it can be hard to determine what makes a bucket "open" or "closed". Disabling for now until I determine a better way to handle it.

#33 - Public-ness is not accurate - Using boto now fixes this
#32 - Buckets in bucket-stream form return 'not found' - s3scanner.py now parses the bucket name out and ignores the region
#43 - Cancelling bucket dumping doesn't work - Implicitly fixed because now the dump process is not in the foreground.

The travis-ci config was changed to allow for 4 total jobs: run Python 2.7 and 3.6 and run each version with and without AWS credentials configured.
A testing requirement matrix was created in the wiki to allow for easier tracking of test coverage.
Added tests:
- test_checkBucketInvalidName()
- test_checkAwsCreds()
- test_checkBucketName()
- test_checkBucketWithoutCreds()
Removed tests:
- test_checkIncludeClosed()
- test_outputFormat()