Fix donation counter

Only works when you donated during this session, but doesn't brake donation flow.
Fixed sync_to_salesforce project sync.

- Made sfproject.organization_account optional in model.
- Added exception handling to project save method.
- sfproject.organization_account now defaults to Nothing when project plan not found.
Removed redundant pass
Merge pull request #442 from jfterpstra/salesforce1

Fixed sync_to_salesforce project sync.
Merge pull request #443 from gannetson/fixing-small-insects

Fix donation counter
Don't let anonymous users create monthly orders.

BB-650 #close
Don't lose anonymous user payment profile.
Don't adjust project phases in fund app.
Update OrderItemMixin to be consistent with DRF 2.3.6.
Merge pull request #444 from benkonrath/order-payment-fixes

Order payment fixes
Add payment cancel (delete) to Payment REST API.
Add API for current payment and use it instead of the REST API.

This commit also includes:

* Remove order unload / reload code in Ember.
* Better error messages on payment error.
* Redirection to item list (voucher or donation) on payment error.

BB-655 #close
Merge pull request #445 from benkonrath/order-payment-fixes

Order payment fixes
Use modelFor('currentOrder') to get voucher list.
Move DonationPreview to projects.js.
Small Ember model cleanups.
Remove donations from voucher orders and remove vouchers from donations.

BB-648
Catch exceptions from DocData when generating payment url.
Small cleanup of DonationSerializer.
Merge pull request #446 from benkonrath/order-voucher-payment-cleanup

Order voucher payment cleanup