Support s3 URIs.

toURL() fails if the URI's scheme is s3. Since the URI gets converted
to a string, just return toString().

src/main/java/org/cellprofiler/imageset/ImageFile.java

@@ -109,25 +109,21 @@ public String getPathName() {
 					int lastSepIndex = path.lastIndexOf("/");
 					if (lastSepIndex <= 0) {
 						final URI uriOut = new URI(uri.getScheme(), uri.getHost(), null, null);
-						pathName = uriOut.toURL().toString();
+						pathName = uriOut.toString();
 					} else {
 						final URI uriOut = new URI(
 								uri.getScheme(), 
 								uri.getHost(), 
 								path.substring(0, lastSepIndex),
 								null);
-						pathName = uriOut.toURL().toString();
+						pathName = uriOut.toString();
 					}
 				}
 			} catch (URISyntaxException e) {
 				LoggerFactory.getLogger(getClass()).info(
 						"Failed to extract metadata from badly formed URL: " + 
 						uri.toString());
 				return null;
-			} catch (MalformedURLException e) {
-				LoggerFactory.getLogger(getClass()).warn(
-						String.format("Failed to reconstitute path from URL, \"%s\"", uri.toString()));
-				return null;
 			}
 		}
 		return pathName;