Fix how the proxy adds a signature for Boku

This was causing a KeyError:
http://sentry.dmz.phx1.mozilla.com/marketplace-payments-alt/payments-alt-solitude-proxyallizomorg/group/19206/
turn off BANGO_USE_USER_ID to allow regression testing (bug 1003248)
Merge pull request #244 from andymckay/1003248

turn off the identity stuff
Merge pull request #243 from kumar303/sig-error

Fix how the proxy adds a signature for Boku
Configure Boku on payments-alt
add in provider to the log (bug 1007192)
Merge pull request #245 from andymckay/1007192

add in providers (bug 1007192)
a bit more logging (bug 1007801)
Merge pull request #246 from andymckay/1007801

add in logging of url so we can see where access is being requested for
Add filter to /boku/product/ API (bug 1008443)

- Add field filter for seller_product
- Add test
Merge pull request #247 from JaredKerim-Mozilla/1008443

Add filter to /boku/product/ API (bug 1008443)
Fix flaky tests (bug 1008457)

- Sort lists of ids for consistent test behaviour
Merge pull request #248 from JaredKerim-Mozilla/1008457

Fix flaky tests (bug 1008457)
create a whitelist of urls (bug 1009710)
Merge pull request #249 from andymckay/1009710

allow nagios into solitude
commas, damn commas
Use only relative paths (bug 1009902)

- Remove DRF monkey patch
- Add relative path fields
- Update serializers
- Update tests
Merge pull request #250 from JaredKerim-Mozilla/1009902

Use only relative paths (bug 1009902)
bump django (bug 1010611)
Allow deletion of SellerProductBoku (bug 1011705)

- Remove deletion override in view
- Update test