Remove the contact picker feature
Remove the contact picker feature

Removal of the ChooseEmailContacts method and the EmailContact class.
It wasn't working on Universal so we decided to remove it since it's
not commonly used.

Resolves: #122.

MarkerMetro/MarkerMetro.Unity.WinIntegration,hungweng/MarkerMetro.Unity.WinIntegration,cedw032/MarkerMetro.Unity.WinIntegration