added comments on sha_pad function working
Added a documentation
Added command line mode to calculate both text SHA1 and file SHA1 function
changed the file as well as text handling options
updated the documentation
Create README.md
All she related functions switched to shalib.h so now we can include the shalib.h in our project and calculate the sha1.

Refer to readme.md for usage detail.
main.c used to show the use only, the actual function and code is on
shalib.h
Merge branch 'pr/1'

Conflicts:
	.DS_Store
	README.md
	main.c
	shalib.h