Introduce IConfigFile, JsonConfigFile class interfaces

* tests/serializers/JsonConfigFileTest.cpp: Introduce unit tests.
* Resources/tests/json/config.json: Resource file for unit test.

* IValueDeserializer: Rename type definitions.
* IValueSerializer: Rename type definitions.

* CMakeLists.txt: Change NOM_BUILD_* variables from options to regular
set vars; this allows us to toggle the variables without rebuilding
project files (a time consuming venture).

* CMakeLists.txt: Introduce NOM_BUILD_SERIALIZERS_UNIT variable.

* tests/CMakeLists.txt: Fix build errs when running unit tests with
regard to the unit test template.
Add UnitTestTemplate.[cpp|hpp] to sublime project file