add options.excludeModule to specify external common used module

[dickeylth]

add options.excludeModule to specify external common used module that should not be processed by CommonsChunkPlugin, to compatible with situations where both CommonsChunkPlugin and webpack.externals defined may cause error for external module.

Ref issue: #2066

• options.excludeModule
  • type: (RegExp | Function)
  • default: function () { return false; }
  • Specify common used module filter regexp / function to exclude from CommonsChunkPlugin process logic.

[zhoujiantao]

please example?

[sokra]

fixed