Allow custom cache dir

We are running oh-my-zsh on a shared install and the only issue is each
user having a custom cache dir. This will allow us to set the cache dir
to ZSH_CACHE_DIR=~/oh-my-zsh/cache/ .

lib/completion.zsh

@@ -38,7 +38,7 @@ cdpath=(.)
 
 # Use caching so that commands like apt and dpkg complete are useable
 zstyle ':completion::complete:*' use-cache 1
-zstyle ':completion::complete:*' cache-path $ZSH/cache/
+zstyle ':completion::complete:*' cache-path $ZSH_CACHE_DIR
 
 # Don't complete uninteresting users
 zstyle ':completion:*:*:*:users' ignored-patterns \

oh-my-zsh.sh

@@ -14,6 +14,13 @@ if [[ -z "$ZSH_CUSTOM" ]]; then
     ZSH_CUSTOM="$ZSH/custom"
 fi
 
+# Set ZSH_CACHE_DIR to the path where cache files sould be created
+# or else we will use the default cache/
+if [[ -z "$ZSH_CACHE_DIR" ]]; then
+  ZSH_CACHE_DIR="$ZSH/cache/"
+fi
+
+
 # Load all of the config files in ~/oh-my-zsh that end in .zsh
 # TIP: Add files you don't want in git to .gitignore
 for config_file ($ZSH/lib/*.zsh); do