move resumablerequestreader to pkg

Docker-DCO-1.1-Signed-off-by: Cristian Staretu <cristian.staretu@gmail.com> (github: unclejack)
server/buildfile.go -> builder/builder.go; add maintainers file

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)
Add Go 1.2 to Travis so we make sure we keep retrocompat for a little while

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)
Merge pull request #7272 from unclejack/create_httputils_pkg

move resumablerequestreader to pkg/httputils
Merge pull request #7292 from erikh/buildfile_move

server/buildfile.go -> builder/builder.go
Merge pull request #7311 from tianon/travis-old-go

Add Go 1.2 to Travis so we make sure we keep retrocompat for a little while
Move parsing functions to pkg/parsers and the specific kernel handling
functions to pkg/parsers/kernel, and parsing filters to
pkg/parsers/filter. Adjust imports and package references.

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)