Add contrast module

[Mridul97]

Fixes #157

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Thanks!

[Mridul97]

Added Contrast Module! The module will accept values between -100 and 100!
Some screenshots of the output:

Original Picture:

Contrast : 30

Contrast : 70

[jywarren]

This is looking great, but I think it may need to be rebased since some time has passed. But very grateful for this new module!!!

[Mridul97]

I have rebased it. Please have a look! 😃

[jywarren]

Hmm, do you know why the tests are failing? If it seems unrelated to your work you could close and reopen to rerun the tests...

Thanks @Mridul97 !!

[Mridul97]

In the job log, It is showing: Error: Cannot find module './modules/Contrast' from '/home/travis/build/publiclab/image-sequencer/src'. Trying to figure out why this is happening.

[Mridul97]

Its solved. Please have a look! 😃

[jywarren]

Perfect, great work!!!

[jywarren]

Wow, this project is really moving fast! So many new modules... 👍

You've really been doing good work :-)