Adding Welcome / Intro screens in malaria app

[Ebaneck]

Add Intro screens in the malaria app as a great way of showcasing the major features of the app.

The user can navigate through each slide using swipe gesture or using the next button.

[Ebaneck]

Proposed new intro for Malaria android app.

Feedback is welcome!!

[ashu-dadhich]

Are you working on it @Ebaneck ?

[Ebaneck]

Hello @top-gun007 I already sent in a pull request.
Link: #117

[chhavip]

@yatna @MeepyMay Will this be a required addition to the application?

[yatna]

@chhavip I think we can add this because we discussed about it during the last GSoC but couldn't add due to lack of time.

[m-murad]

@yatna @chhavip @anubhakushwaha
this PR adds images to the project that will be included in the APK.
We should reduce the size of these images by using PNGCrush or some similar software.

If this PR is to be merged and the original author is not available to update the PR should I make the changes