Change the tests path if the modules folder is customized

[vladejs]

Currently I can set modulesPath variable to any location, for example: /client/imports/modules/, but when I create a component/container, tests are still being created under /client/modules/.

Tests should always follow the path of modules folder. The ideal scenario is to enable another setting on mantra-cli.yml:

testsPath = testsPath || modulesPaths.

That way, if I set a testsPath setting, mantra uses that path to generate tests. Otherwise, it uses modulesPath.