Expose Yamcs archive through a web api

A first go at a web api, it uses chunked transfer because we
don't want to store to a temp file just because of the
content-length. Chunks can be pretty small, they are aligned
with the incoming data from the ReplayServer.

Only parameters & packets are supported, and profiles are
supposed to be predefined in ~/.yamcs/profiles/

Example usage:
http://localhost:8066/local/archive/packets?start=2007-08-01T12:34:00&stop=2013-08-23T18:34:00&profile=packet-test

or

http://localhost:8066/local/archive/parameters?start=2007-08-01T12:34:00&stop=2013-08-23T18:34:00&profile=parameter-test

where ~/.yamcs/profiles contains two files, packet-test and param-test, each containing a list of fully qualified packets resp. parameters, separated by newlines.