Add a crash handler part 2 v2

Hi Matt,

This completes the second part of two of the crash handler.

This part utilizes vmcore-dmesg, part of kexec-tools, to extract the dmesg buffer from the vmcore memory dump. When booting from runlevel 3, the contents of the dmesg buffer are saved on the test results partition of the LuvOS media. Also, functionality is added to inform the user of all the actions taken.

Additionally, the kexec-tools recipe is modified to explicitly select the 2.0.7 version of kexec-tools. This provides tighter control (and reproducible build across hosts) of the version used. The version is important as previous versions will not be able to parse the dmesg buffer correctly due to changes in the Linux kernel.

Changes from v2.
* The kexec-tools_2.0.7.bb recipe is moved from meta-luv to meta. This is to be more inline with the upstream Yocto Project. However, this is not the same patch that was submitted upstream because we jump from 2.0.4 to 2.0.7 while submitted change jumps to 2.0.6 to 2.0.7.

* The kexec-tools_git recipe and its patches were removed in a separate patch to separate the changes to meta-luv from the changes to meta.

* It is not necessary to explicity select the kexec-tools version in the LuvOS distro conf file.

Thanks and BR,
Ricardo