Enable discovery and use of nvm installed via homebrew.

https://github.com/Homebrew/homebrew/blob/master/Library/Formula/nvm.rb#L27

plugins/available/nvm.plugin.bash

@@ -6,7 +6,13 @@ cite about-plugin
 about-plugin 'node version manager configuration'
 
 export NVM_DIR="$HOME/.nvm"
-[ -s "$NVM_DIR/nvm.sh" ] && . "$NVM_DIR/nvm.sh"  # This loads nvm
+# This loads nvm
+if command -v brew &>/dev/null && [ -s $(brew --prefix nvm)/nvm.sh ]
+then
+  . $(brew --prefix nvm)/nvm.sh
+else
+  [ -s "$NVM_DIR/nvm.sh" ] && . "$NVM_DIR/nvm.sh"
+fi
 
 if ! command -v nvm &>/dev/null
 then