chore: fixing travis ci build failure due directory permissions [+]

plus caching for revoked key hashes blacklist

Signed-off-by: Marco Aurélio da Silva <marcoonroad@gmail.com>

.travis.yml

@@ -14,3 +14,13 @@ env:
 os:
   - linux
   - osx
+
+before_install:
+  - sudo mkdir -p $HOME/.hieroglyphs
+  - sudo mkdir -p $HOME/.hieroglyphs/blacklist
+  - sudo chmod -R a+rw $HOME/.hieroglyphs
+  - cd $HOME/.hieroglyphs/blacklist && git init --bare --shared=all && cd $OLDPWD
+
+cache:
+  directories:
+    - $HOME/.hieroglyphs