Add test enviroment to bundler setup on tests

This made possible to run individual tests with something like:

ruby  -Itest/ test/test_spinning_cursor.rb -v -n "/allow you to change the banner/"

Necessary to faster repeating individual tests.
Fix Issue #17

It was just a "timing" issue.
Delaying sometimes was falling before and sometimes after banner changing.
Merge pull request #20 from abinoam/issue17

Fix issue #17 (non-deterministic test due to race conditions)