[*] Updated Stellar SDK to 1.0.0-alpha0

[overcat]

This PR upgrades the Stellar SDK to the latest version. I have no experience in developing Android apps at all, so I only made minimal changes. Please let me know if there are any issues.

[silent-grass]

@overcat Thank you so much for your work!

I already have local branch with necessary changes for 1.0.0-alpha0 release (also Assets rework and TrustLineEntryFlag mapper). I have compared one with yours and make necessary changes.

[overcat]

Hi @silent-grass. Cool! could you please submit your PR to this repository? If possible, I would like to use it as a reference for other users. Thank you.

@overcat Thank you so much for your work!

I already have local branch with necessary changes for 1.0.0-alpha0 release (also Assets rework and TrustLineEntryFlag mapper). I have compared one with yours and make necessary changes.

[silent-grass]

@overcat I apologize for the late response. PR with Stellar SDK 1.0.0-beta0 support.

[overcat]

@overcat I apologize for the late response. PR with Stellar SDK 1.0.0-beta0 support.

Thanks! Very cool!