Fix Travis-CI for macOS and libtorrent 1.1.x

.travis.yml

@@ -117,7 +117,7 @@ install:
       PATH="/usr/local/opt/ccache/libexec:$PATH"
 
       brew update > /dev/null
-      brew install ccache colormake boost libtorrent-rasterbar openssl qt zlib
+      brew install ccache colormake boost openssl qt zlib
       brew link --force qt zlib
 
       if [ "$build_system" = "cmake" ]; then
@@ -147,6 +147,32 @@ install:
 
       sudo dpkg -i "$HOME/travis/deb/libtorrent-rasterbar-dev_1.2.x_amd64.deb" "$HOME/travis/deb/libtorrent-rasterbar10_1.2.x_amd64.deb"
     fi
+    - |
+    if [ "$libt_branch" = "RC_1_1" ] && [ "$TRAVIS_OS_NAME" = "osx" ]; then
+      wget https://builds.shiki.hu/travis/brew/1_1/version
+      if ! cmp --quiet "version" "$HOME/travis/brew/1_1/version" ; then
+        echo "Cached files are different from server. Downloading new ones."
+        # First delete old files
+        rm -r "$HOME/travis/brew/1_1"
+        mkdir "$HOME/travis/brew/1_1"
+        cp "version" $HOME/travis/brew/1_1
+        cd "$HOME/travis/brew/1_1"
+        wget https://builds.shiki.hu/travis/brew/1_1/libtorrent-rasterbar.rb
+        wget https://builds.shiki.hu/travis/brew/1_1/bd36a4b440aa138a88e375c1a3b672f1a1bc6606e7866fc3415b6b98fa49e771--libtorrent-rasterbar-1.1.13.high_sierra.bottle.tar.gz
+      fi
+      # Copy custom libtorrent bottle to homebrew's download cache so it can find and install it
+      # Also install our custom libtorrent formula by passing the local path to it
+      # These 2 files are restored from Travis' cache.
+      cp "$HOME/travis/brew/1_1/bd36a4b440aa138a88e375c1a3b672f1a1bc6606e7866fc3415b6b98fa49e771--libtorrent-rasterbar-1.1.13.high_sierra.bottle.tar.gz" "$(brew --cache)/downloads"
+      brew uninstall libtorrent-rasterbar
+      brew install "$HOME/travis/brew/1_1/libtorrent-rasterbar.rb"
+
+      # NOTE about the bottle name
+      # The part before the "--" characters is a sha256 hash of the string
+      # of the URL homebrew itself would use to download the bottle.
+      # In this case the URL is the following:
+      # http://127.0.0.1/libtorrent-rasterbar-1.1.13.high_sierra.bottle.tar.gz
+    fi
   - |
     if [ "$libt_branch" = "RC_1_2" ] && [ "$TRAVIS_OS_NAME" = "osx" ]; then
       wget https://builds.shiki.hu/travis/brew/version