Convert non-breaking space in yaml to normal space

[northtyphoon]

Is this a BUG REPORT or FEATURE REQUEST?:
FEATURE REQUEST

What happened?:

If task yaml file has non-breaking space, it may cause some unexpected result. For example, if there is a non-breaking space at the beginning of the cmd step, the step will be skipped in the execution.

 - cmd

What did you expect to happen?:

Convert non-breaking space to normal space.

Here is an example travis-ci/travis-core#227