fix 1261: change parameter to int/bool according to data-type

when executing a VCA primitive, parameter values are always a
string (defined at yang model), but key 'data-type' can indicate
that this is a STRING, INTEGER or BOOLEAN. In case of not a string
data is converted to the target type

Change-Id: I77babb1859b99df9290373deb3568686663d2015
Signed-off-by: tierno <alfonso.tiernosepulveda@telefonica.com>