bench: Make template directory dynamic

[scruzin]

Resolving Issue #60, required changing the template directory from "t" to "cmd/oceanbench/t".

In standalone mode, however, it is normal to execute ./oceanbench from cmd/oceanbench. Therefore the latter is the working directory, which means the templates are not found.

Therefore the template directory should be dynamic.

[scruzin]

Note that running oceanbench from the repo level level permits the template files to be found, but moves the problem to the static files, which cannot be found.

[scruzin]

The check needs to be a bit more sophisticated to detect whenever we're running locally, not just in standalone mode. @trekhopton

[trekhopton]

resolved in PR #65