Add function for getting the timestamp in nanoseconds
Add function for getting the timestamp in nanoseconds

The timestamp is returned as an integer number of nanoseconds since the Unix
epoch.

Signed-off-by: Michele Tartara <05f7077a2c6cbbdc4af4ba42e3ef89a0df846179@google.com>
Reviewed-by: Helga Velroyen <2d0126b1ec6f9ec5cbec4a7012aa14faeaef10f5@google.com>

yiannist/ganeti,ganeti-github-testing/ganeti-test-1,onponomarev/ganeti,dimara/ganeti,andir/ganeti,apyrgio/snf-ganeti,bitemyapp/ganeti,mbakke/ganeti,ganeti/ganeti,mbakke/ganeti,yiannist/ganeti,ganeti-github-testing/ganeti-test-1,yiannist/ganeti,ganeti/ganeti,ganeti/ganeti,grnet/snf-ganeti,andir/ganeti,onponomarev/ganeti,leshchevds/ganeti,leshchevds/ganeti,leshchevds/ganeti,apyrgio/ganeti,mbakke/ganeti,dimara/ganeti,bitemyapp/ganeti,apyrgio/ganeti,andir/ganeti,grnet/snf-ganeti,apyrgio/snf-ganeti