Fix Outlook and Windows Attachment issues, resolve merge conflict

[MaxPMagee]

This PR is based on work that @kacyn did for the original PR here
#65

This also supports attachments in Outlook within Android

[bruscantini]

Are there any drawbacks to using this change?
Can you explain it? Do all clients except Outlook have a non-null "attachment" option?
Thanks,

[MaxPMagee]

Unfortunately, I was not the original author, I just resolved the merge conflicts that cropped up months after the original PR. As I say here, I need someone who is a domain expert to review it.
#65 (comment)

[bruscantini]

@MaxPMagee gotcha! Upon checking his comments in that PR, I think the first change is just for cases where the email has an attachment. I guess Outlook needs that when sending an attachment.

The second change is absolutely necessary for Outlook to work. I've actually been using that change in my app for some time now. I just had to upgrade the lib recently so I've had to revisit it :)

[mars-lan]

@bruscantini I think you meant to tag @MaxPMagee not me?

[bruscantini]

Yup @mars-lan sorry about that one. It wasn't prefilling his username for me.

[project-sense]

Is anyone looking into it, facing issue with outlook. Body not rendering when isHtml is set to true