Capitalize JWT algorithm used for webhook

While the JWT standard doesn't explicitly say that algorithm names must
be capitalized, all of its examples are capitalized (e.g. 'HS256'
instead of 'hs256').  The lower-case name caused a spurious signature
failure for me.
Better issuers and programs arrays in system and issuer responses
0.2.9
Merge pull request #77 from tgs/capitalize-jwt-algorithm

Capitalize JWT algorithm used for webhook
Merge pull request #82 from mozilla/better-issuers-programs-response

Better issuers and programs arrays in System.toResponse and Issuer.toResponse
Fix error when requesting badge instances of a user with no badges
Merge pull request #84 from mozilla/user-instances-fix

Fix error when requesting badge instances of a user with no badges