Address Issue #7 by making kleiDust.loadTemplate use fs.readFileSync.

This patch addresses issue #7 as discussed at [github.com/klei-dev/dust/issues/7](https://github.com/klei-dev/dust/issues/7).

The `kleiDust.loadTemplate` method is modified to load templates synchronously in order to allow templates a chance to be added to the cache, even when loaded many times in quick succession.

A test case is included (in `test/dust.js`).  Two new files were added to `test/templates` in support of this test.