Check if toolchain was rebuilt

[holzingk]

If toolchain was rebuilt suggest users to rebuild OTP (with --configure false). Helps avoiding strange behaviours.

[holzingk]

grisp-software buildscripts now create files containing build revision.

[eproxus]

Options we now have:

1. Copy buildrev into the built OTP installation (or outside as not to copy it onto the SD-card?)
2. Incude grisp-buildinfo.h into the VM and print it somewhere
3. Copy grisp_buildinfo.hrl somewhere for the GRiSP runtime to include