Don't use basenames for imported modules.

Basically this is preventing us from compiling
js files that are not in the current directory, i.e.
./ejs /tmp/sample.js.

This is needed for being able to run under the test262 suite,
as they run their tests from some temporary directory, i.e.
/var/tests/ch07/test.js, and we were failing to run properly.
Add a wrapper to compile + run a test case.

This is needed for test262, as they expect a command file,
which they invoke on each test file they have.
Add a small script to invoke the test262 on us.

We are assuming there's a test62/ directory next to echo-js/
Watch out for the return code of our binary.

We need to check that everything ran smoothly - otherwise,
it's a clear error.
Merge pull request #46 from carlosalberto/test262-integration

Test262 integration