clean up whitespace in repo descriptions

This cleans up the whitespace in the description item, since the
XML parsing will include the linefeeds and indenting in the description.

app/src/test/java/org/fdroid/fdroid/data/RepoProviderTest.java

@@ -166,7 +166,7 @@ public class RepoProviderTest extends FDroidProviderTest {
             assertRepo(
                     defaultRepos.get(i),
                     reposFromXml[offset + 1], // address
-                    reposFromXml[offset + 2], // description
+                    reposFromXml[offset + 2].replaceAll("\\s+", " "), // description
                     Utils.calcFingerprint(reposFromXml[offset + 7]), // pubkey
                     reposFromXml[offset]      // name
             );