[api] fix request schema

grouped can appear more than once, but it always has one id

This left unnoticed, as request/show did not validate due to the usage of
send_data, which is now fixed. Also avoiding double render errors if an
exception happens
[webui] do not simply reset the cache but also write it to the backend

Really fixes #485
[api] add more features to the request RNG

I also added a test case to check our existant schema - to great horror
it's all failing -> issue #489
[api] fix TODOed test case for code quality
[webui] fix submit request dialog

For some reason I set the list_small url as autocomplete_url, that's obviously
not working
[api] move build and source controller outside the XML matcher

Some routes in there actually reply text content
[backend] use standard locking in BSFileDB

With the simple lock used before, a rewrite+rename
could lead to data loss.
[activexml] remove method_missing to ease debugging

This catch all makes it very hard
[webui] remove webui_package model in favor package
[webui] fix filtered project status (issue #492)
[webui] @package.api_obj is @package now
[webui] request ids should be integers

fixes #169
[webui] get rid of WebuiGroup - just a thin wrapper anywy
[webui] load the real target project's request list, not the initial one
[webui] requests created by me are just outgoing requests

no matter if they are new or review
[webui] fix for project hiding in the workerstatus
[webui] fix forwarding requests
[webui] catch missing packages
[webui] test invalid package
[webui] fix dependency view