Fix FileLocator path separator

File.separator is the separator used in subdirectory paths ('/'), whereas
File.pathSeparator is used in $PATH for separating multiple paths (':').
Using the wrong separator worked on OS X since the /var/folders subdir
could be created (":ss-cache") but failed on (Linux?) ci.md-5.net since
/tmp:ss-cache cannot be created (nor it should it be). With this change,
the path should be /tmp/ss-cache, as expected.

src/main/java/net/md_5/specialsource/util/FileLocator.java

@@ -41,7 +41,7 @@ public class FileLocator {
 
     private static File download(String url) throws IOException {
         // Create temporary dir in system location
-        File tempDir = new File(System.getProperty("java.io.tmpdir") + File.pathSeparator + "ss-cache");
+        File tempDir = new File(System.getProperty("java.io.tmpdir") + File.separator + "ss-cache");
         if (!tempDir.exists()) {
             tempDir.mkdirs();
         }