Update the plugins managment. Add the function 'omz-plugin' (inspired from bash-it)

plugins/available/fancy-ctrl-z/README.md

@@ -0,0 +1,14 @@
+# Use Ctrl-Z to switch back to Vim
+
+I frequently need to execute random command in my shell. To achieve it I pause 
+Vim by pressing Ctrl-z, type command and press fg<Enter> to switch back to Vim.
+The fg part really hurt sme. I just wanted to hit Ctrl-z once again to get back 
+to Vim. I could not find a solution, so I developed one on my own that 
+works wonderfully with ZSH
+
+Source: http://sheerun.net/2014/03/21/how-to-boost-your-vim-productivity/
+
+Credits: 
+- original idea by @sheerun
+- added to OMZ by @mbologna
+