Merge pull request #17 from lhcb-org/dev/rpm-provides

Dev/rpm provides
cmd-install-project: first stab
cmd-install: install multiple RPMs in one go
doc: update docs
lhcbconfig: fixup relocate-file (for /opt/lcg/external)
doc: updates
all: use newCommand to spawn new os/exec.Cmd to be part of a process-group
all: kill sub-processes by way of their process-group