titaniumenv: add 7.1 SDK and make it the default

pkgs/development/mobile/titaniumenv/build-app.nix

@@ -47,7 +47,7 @@ in
 stdenv.mkDerivation {
   name = stdenv.lib.replaceChars [" "] [""] name;
   inherit src;
-  
+
   buildInputs = [ nodejs titanium alloy jdk python which file ] ++ stdenv.lib.optional (stdenv.system == "x86_64-darwin") xcodewrapper;
   
   buildPhase = ''
@@ -84,7 +84,8 @@ stdenv.mkDerivation {
           titanium config --config-file $TMPDIR/config.json --no-colors android.sdkPath ${androidsdkComposition}/libexec
 
           export PATH=$(echo ${androidsdkComposition}/libexec/tools):$(echo ${androidsdkComposition}/libexec/build-tools/android-*):$PATH
-          
+          export GRADLE_USER_HOME=$TMPDIR/gradle
+
           ${if release then
             ''titanium build --config-file $TMPDIR/config.json --no-colors --force --platform android --target dist-playstore --keystore ${androidKeyStore} --alias ${androidKeyAlias} --store-password ${androidKeyStorePassword} --output-dir $out''
           else