Support injection of scheduler options from an environment

[teojgo]

The concept that was discussed is the support of the following:

environs = [{
	'name': 'gnu',
	'sched_bind_options': ['--uenv-file={env.extras["uenv_file"]}',
						   '--uenv-mount={env.extras["uenv_mount"]']
}]

Using the above syntax, the env refers to the actual environment and use its extras.

[vkarak]

Just to be clear, the above syntax is proposed for the partition definition.