(change:minor) Code clean-up.
(change:minor) In dcs::testbed::lq_application_manager class, skip
control if no observation is found.

(new:minor) In dcs::testbed::lq_application_manager class, added counter
to count the number of times control has been skipped.
(new:minor) In dcs::testbed::rain::response_time_sensor class, added some debugging messages.
(change:minor) In dcs::testbed::rain::workload_driver class, removed steady-state thread monitor.
(change:minor) In dcs::testbed::rain::response_time_sensor, removed use of auxiliary variable 'new_data_'.
(change:minor) In dcs::testbed::rain::response_time_sensor class, code clean-up.
(change:minor) In dcs::testbed::lq_application_manager class, added some debugging messages.
(new:minor) In dcs::testbed::lq_application_manager class, added constructor for passing matrices Q and R
(bug-fix:minor) Wrong size for the R matrix.
(bug-fix:minor) In dcs::testbed::lq_application_manager, normalize the
observed performance measure wrt the target value.
(bug-fix:minor) Performance taget and SLO should be expressed in milliseconds (well this is not actually true; we have to better define this).
(bug-fix:minor) In dcs::testbed::lq_application_manager class, control
output is the same of model output.
(bug-fix:major) Forgot to set the model output vector.
(new:major) Added application manager implementation based on (Padala et al., 2009).
(change:minor) In dcs::testbed::lq_application_manager class, code clean-up.
(new:minor) In system identification strategy classes, add member functions: y(), u(), y_hat()
(bug-fix:major) In dcs::testbed::padala2009_application_manager class, the reference value used to computer opt_s should have already been normalized.
(change:minor) Added some debugging messages.
(bug-fix:minor) Padala2009 application manager should use an input delay equal to 1.
(change:major) Added new state-space transformations. Bug fixes and optimizations.