Add invite person checkbox to "add person" flow

[CeciliaHinga]

From tenfour-archive created by caharding: ushahidi/tenfour-archive#1324

When a user is invited via "add person" there should be a checkbox (pre-checked) that says "Invite user to TenFour" at the bottom of the flow

[CeciliaHinga]

Also scope CSV upload

[CeciliaHinga]

I would recommend that the copy read "Invite person by email to TenFour" or "Send this person an email invite to download the TenFour app"

I know it's wordy, but we had quite a few people during UT confused that adding a person would automatically send them a text message inviting them or adding them (if they didn't add in an email) and the whole process was confusing as to what an 'added person' would end up seeing.

[CeciliaHinga]

1st choice sounds good to me