Added support classes for variables substitution

Signed-off-by: Oleg Nenashev <nenashev@synopsys.com>
Added getters to the installer

Signed off by Oleg Nenashev <nenashev@synopsys.com>
Added substitution of global and node variables.

Signed-off-by: Oleg Nenashev <nenashev@synopsys.com>
Merge pull request #1 from synopsys-arc-oss/variables_support

Variables support