Creates the R script to compute the overhead

It creates the file calc_regression.r that computes the overhead of two
versions of pills with relation to the vanilla version. This two
versions are: executions of pils with TALP; and executions of pils with
TALP and TALP regions. This script also creates a plot that shows the
linear regression.

It also adapts the job.sh to automatically report overhead of two
installations of DLB: dlb/git; and dlb/testing.

Signed-off-by: JOAN VINYALS YLLA CATALA <joan.vinyals@bsc.es>