update install files

* correct bad paths in install.sh (thanks @pidgypost)
* update brew install script
* update nvm installation to work correctly

fixes #6 and fixes #7

install/brew.sh

@@ -1,5 +1,12 @@
 #!/bin/sh
 
+if test ! $(which brew); then
+    echo "Installing homebrew"
+    ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
+fi
+
+echo "Installing homebrew packages..."
+
 # cli tools
 brew install ack
 brew install tree
@@ -20,3 +27,5 @@ brew install highlight
 brew install nvm
 brew install z
 brew install markdown
+
+exit 0