Update rawimage.py

[darrencpagan]

Bug found that when using this images series 'raw-images' option and calling the first image, the skip bytes wasn't being properly accounted for.

This change fixes it.

[pep8speaks]

Hello @darrencpagan! Thanks for opening this PR. We checked the lines you've touched for PEP 8 issues, and found:

• In the file hexrd/imageseries/load/rawimage.py:

Line 112:67: E261 at least two spaces before inline comment
Line 112:68: E262 inline comment should start with '# '
Line 112:80: E501 line too long (115 > 79 characters)

[donald-e-boyce]

Good catch. This is fine, but you could also have done:

self.f.seek(self.skipbytes, 0)

The second argument (0) means absolute positioning from the beginning of the file.

Change it if you like or just merge. I am approving the pull request.