repomanager: add ToolchainRepo class
xmldefaults: add new buildtype armhf_linaro48

this buildtype is a copy of armhf but with additional
values for toolchaintype and toolchainver.

This will be used by the toolchain extractor command.
toolchainextract: add first version of toolchainextract code

this includes the toolchain and debpkg.py files
hdimg: also use kpartx in grubinstaller2 class

This is the first step to unifying the grub1 and grub2 code again.
Merge remote-tracking branch 'origin/devel/torbenh/e1.0' into devel/elbe-1.0
debian: add toolchainextract to elbe-buildenv package

Signed-off-by: Manuel Traut <manut@linutronix.de>