Add image parser module

[Mashychev]

No description provided.

[coveralls]

Coverage decreased (-1.09%) to 93.261% when pulling 3288043 on Mashychev:develop into 211f89b on roo-rb:master.

[coveralls]

Coverage decreased (-1.1%) to 93.217% when pulling 8b8810a on Mashychev:develop into 211f89b on roo-rb:master.

[coveralls]

Coverage decreased (-0.05%) to 94.298% when pulling a420130 on Mashychev:develop into 211f89b on roo-rb:master.

[coveralls]

Coverage increased (+0.09%) to 94.442% when pulling 28809ff on Mashychev:develop into 211f89b on roo-rb:master.

[simonoff]

We need to have this functionality inside ::Roo::Excelx::Sheet where it best place. So developer can through some call images take all images in sheet.

[coveralls]

Coverage increased (+0.04%) to 94.389% when pulling e74f802 on Mashychev:develop into 211f89b on roo-rb:master.

[coveralls]

Coverage increased (+0.06%) to 94.407% when pulling 59d8d98 on Mashychev:develop into 211f89b on roo-rb:master.

[simonoff]

Better but still not efficient.
You read zip file two times, which is not good.
You can look on process_zipfile_entries method. Where zip file is processed. So you can add extracting images there.

[simonoff]

@Mashychev may be you can found a time and finish this PR?

[stevendaniels]

Replaced with #414