Remove curl from dependencies

Add suport for CentOS 7 and Debian 8

HACKING.md

@@ -2,7 +2,6 @@
 
 ### System dependencies (Ubuntu 14.04 package names)
   - build-essential
-  - curl
   - postgresql-server-dev-9.3
 
 ### Unpacked dependecies
@@ -24,6 +23,11 @@
 
   You can easily install it through the Ruby Version Manager - RVM. Instructions on how to do it can be found at http://rvm.io
 
+  It is expected to work with:
+
+  - 2.1.5 Debian 8
+  - 2.0.0 CentOS 7
+
   *NOTE:* If you are using the gnome-shell, or any derivate like terminator, you have to mark on your profile the option to use a "login bash".