Merging @dritter's Node.js segment support.

This is PR #53.
Merge remote-tracking branch 'dritter/dritter/nvm'

README.md

@@ -224,6 +224,7 @@ currently available are:
 * **context** - Your username and host (more info below)
 * **dir** - Your current working directory.
 * **history** - The command number for the current line.
+* **node_version** - Show the version number of the installed Node.js.
 * **rbenv** - Ruby environment information (if one is active).
 * **rspec_stats** - Show a ratio of test classes vs code classes for RSpec.
 * **status** - The return code of the previous command, and status of background jobs.

powerlevel9k.zsh-theme

@@ -472,6 +472,15 @@ prompt_longstatus() {
   [[ -n "$symbols" ]] && $1_prompt_segment "$0" "$bg" "$DEFAULT_COLOR" "$symbols"
 }
 
+# Node version
+prompt_node_version() {
+  local nvm_prompt=$(node -v 2>/dev/null)
+  [[ -z "${nvm_prompt}" ]] && return
+	NODE_ICON=$'\u2B22 ' # ⬢
+
+  $1_prompt_segment "$0" "green" "white" "${nvm_prompt:1} $NODE_ICON"
+}
+
 # rbenv information
 prompt_rbenv() {
   if [[ -n "$RBENV_VERSION" ]]; then