spice payload: Before MidTerm GSoC report

My very first task on gsoc was to make buildrom work with latest codes from coreboot, with that I changed how it used to build coreboot. First I introduced the coreboot kconfig options to buildrom so the user can configure and choose the options for coreboot in the same mainmenu as buildrom.

Some small changes was introduced as a consistent pattern to name the kernel mk files and the possibility to checkout source code with https:// or svn://.
Updated some packages mk files to comply some patterns I introduced.

I still have some changes to introduce but I think it`s already usable. I might push the final bits in the next few days whenever I get a chance to work out my patches.