Rewrite: include some headers to strip.
t/55-rewrite.t: update tests
Merge pull request #71 from duckduckgo/jag/header-strip

Rewrite: Add additional `proxy_set_header`s to strip
Rewrite: proxy_set_header gets set in other ways, too.
Rewrite: Remove extra space.
Merge pull request #73 from duckduckgo/jag/header_more

Rewrite: proxy_set_header gets set in other ways, too.
Rewrite: Workaround for endpoints with no callback functions

This is a workaround that deals with endpoints that don't support callback functions. So endpoints that don't support callback functions return a content-type of 'application/json' because what they're returning is not meant to be executed in the first place. Setting content-type to application/javascript for those endpoints solves blocking due to mime type mismatches.
Merge pull request #74 from duckduckgo/jag/mime

Rewrite: Workaround for endpoints with no callback functions
Test/Block: Fixed an error with load_class.

`load_class` was returning `undef`, which makes accessing `trigger_block_type` an invalid operation. Thanks to @nilnilnil for solving the problem.
Merge pull request #75 from duckduckgo/jag/load

Test/Block: Fixed an error with load_class.
Rewrite: Add proxy_intercept_errors to Spice endpoints.

When we get errors from the endpoint, instead of replying a blank page, it should reply the function instead with no parameters, e.g., ddg_spice_dictionary_definition();. The benefit of doing that is that we know for sure that the Spice failed, and we can do something about it (we know that the Spice failed because it should return Spice.failed('...') when the parameters are not valid).
Rewrite: Moved proxy_intercept_errors to the bottom.
Merge pull request #78 from duckduckgo/jag/failed

Rewrite: Add proxy_intercept_errors to Spice endpoints.