Add --nv, --rocm, --bind flags to build command.

[cclerget]

Description of the Pull Request (PR):

Add --nv, --rocm, --bind flags to build command. Those are taking effect during build for both post and test sections.

This fixes or addresses the following GitHub issues:

• Fixes Feature: Allow --nv during build #1216

Before submitting a PR, make sure you have done the following:

• Read the Guidelines for Contributing, and this PR conforms to the stated requirements.
• Added changes to the CHANGELOG if necessary according to the Contribution Guidelines
• Added tests to validate this PR and tested this PR locally with a make testall
• Based this PR against the appropriate branch according to the Contribution Guidelines
• Added myself as a contributor to the Contributors File

Attn: @singularity-maintainers

[dtrudg]

Looks reasonable to me, but could you add a basic test into:

https://github.com/hpcng/singularity/blob/master/e2e/gpu/gpu.go

... or in the build tests. Gated by require.Nvidia / require.Rocm?

[cclerget]

Looks reasonable to me, but could you add a basic test into:

https://github.com/hpcng/singularity/blob/master/e2e/gpu/gpu.go

... or in the build tests. Gated by require.Nvidia / require.Rocm?

Tests added