Anchors and reorder in dependency lists of README.md

Dependency headers for OSes needed anchors to work with links from
content list. Reordered OSes in content list to match headers
(all Linuxes first, Mac OS X last)

README.md

@@ -16,8 +16,8 @@
 * [Dependencies](#dependencies)
   * [For Debian/Ubuntu](#for-debianubuntu)
   * [For FreeBSD 10](#for-freebsd-10)
-  * [For OS X](#for-os-x)
   * [For Arch Linux](#for-arch-linux)
+  * [For OS X](#for-os-x)
 * [Building](#building)
 * [Community](#community)
 * [Contributing](#contributing)
@@ -272,18 +272,22 @@ and what is currently being worked on:
 
 ## Dependencies
 
+<a name="for-debianubuntu"></a>
 ### Ubuntu/Debian
 
     sudo apt-get install libtool autoconf automake cmake libncurses5-dev g++
 
+<a name="for-freebsd-10"></a>
 ### FreeBSD 10
 
     sudo pkg install cmake libtool sha
 
+<a name="for-arch-linux"></a>
 ### Arch Linux
 
     sudo pacman -S base-devel cmake ncurses
 
+<a name="for-os-x"></a>
 ### OS X
 
 * Install [Xcode](https://developer.apple.com/) and [Homebrew](http://brew.sh)