Add support for include library and code-coverage

Feature 1:
1) --i, --I, --include PATH for require.paths, avoid having require("../lib/mylib") in js file  includes use require("mylib") in js file.  and run vows --include "../lib" instead.
Feature 2:
2) if --cover-html or --cover-plain is on, start jscoverage in child process, and generate the lib-cov for instrumented lib, and use it for coverage report.