Move alias for ls into lscolors.zsh

Having the ls alias default to `ls --color=auto` caused it to break on
OSX, since the version of ls that ships with OSX doesn't support the
`--color` option.

This change moves the alias into lscolors, since we already have a check
for OSX vs non-OSX (in my case, Linux). This allows the alias to work as
expected on Linux, while the environment variable LSCOLORS provides the
coloring option on OSX.

zsh/aliases.zsh

@@ -3,7 +3,6 @@
 #######################################################################
 # Common aliases across systems
 # ls aliases
-alias ls='ls --color=auto'
 alias ll='ls -l'
 
 # Git aliases

zsh/lscolors.zsh

@@ -39,6 +39,9 @@ then
 
     # Must use either CLICOLOR=1 or ls -G
     export CLICOLOR=1
+else
+    # On Unix, add an alias to display the color always
+    alias ls='ls --color=auto'
 fi
 
 DCFILE="$HOME/.dircolors"