Add "main" option to resolve main content of this library
Add "main" option to resolve main content of this library

I added "main" option to resolve main content of this library from other
libraries (e.g. (wiredep)[https://github.com/taptapship/wiredep]).

TalksLab/metro-bootstrap,HossainKhademian/MetroBootstrap,lgscofield/metro-bootstrap,gencer/metro-bootstrap,anksp21/metro-bootstrap,Jiasm/metro-bootstrap,292388900/metro-bootstrap