Github usernames should allow dash/hyphen ("-") character

[JoA-MoS]

Bug Report or Feature Request (mark with an x)

- [X ] bug report -> please search issues before submitting
- [ ] feature request

OS and Version?

Windows 10

Generator Version

5.5.0

Tools Version

Output from: yo --version
2.0.1
Output from: node --version,
'v9.3.0Output from:npm -v 5.6.0`

Targeted Angular version

5.x.x

Repro steps.

Start generator by typing yo and select Ngx Library

The log given by the failure.

Step 3 requires no special characters

Desired functionality.

allow hyphens in github user names

[JoA-MoS]

generator-ngx-library/app/validators.js

Line 34 in 255c6d9

return /^[a-zA-Z0-9]+$/.test(input) ? true : 'Your github username cannot contain special characters or a blank space';

should be at least this (I am not sure if github allows underscore or other special characters)

 validateGithubUsername: input => {
    return /^[a-zA-Z0-9\-]+$/.test(input) ? true : 'Your github username cannot contain special characters or a blank space';
  },

[JoA-MoS]

I created a pull request into your feature rollup - #145