add init.lua to use the package easily

[alhassanaraouf]

importing package require init.lua in package folder

[ruilya]

I wonder why this was never accepted... Really handy one. Wish there was a vote mechanism for that on github :)

[GourSE]

i assume that he put the file in the awesome config root instead of the awesomewm-screenshot dir

[G2G2G2G]

also several typos in the code and readme.. he has callback in the command string of the scrot_full func which prob does underlying bash errors and extra commas in places

I ended up just deleting all the callback stuff and extra arguments entirely