Add a HOLD state to Phortune and handle unusual states better

Summary:
Ref T2787. When Paypal comes back to us with funds on hold, dead-end the transaction but handle it properly.

Generally, smooth out the user interaction on weird states.

Implement refudnds/cancels for Paypal.

Test Plan: {F215230}

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T2787

Differential Revision: https://secure.phabricator.com/D10667
Implement Phortune charge updates

Summary: Ref T2787. These don't necessarily do a ton yet, but we can get PayPal out of hold, at least.

Test Plan: Updated charges from all providers. Cleared a PayPal hold.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T2787

Differential Revision: https://secure.phabricator.com/D10670
Smooth out Phortune purchase completion flow

Summary:
Ref T2787. Currently, we dump the user back into the application. Instead, give them a confirmation screen and then let them continue.

Also fix a couple of unit tests I adjusted the underlying behavior of somewhat-recently in libphutil.

Test Plan: {F215498}

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T2787

Differential Revision: https://secure.phabricator.com/D10672
Support multiple payment accounts and account switching in Phortune

Summary: Ref T2787. Support multiple payment accounts so you can have personal vs company payment accounts.

Test Plan: See screenshots.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T2787

Differential Revision: https://secure.phabricator.com/D10673
Merge remote branch 'upstream/master'