Test to exercise lustre and curl code.

Add new tests that verifies FS type is lustre when CHPL_AUX_FILESYS
contains lustre and FS type is curl when CHPL_AUX_FILESYS contains
curl.

Also add new "does not contain" operator to skipif parser to support these
tests. The new operator, >= (as opposed to <=), means `<variable>` does
not contain the substring `<value>`. For example, adding this line to a skipif:

```
CHPL_AUX_FILESYS >= lustre
```

means: skip the test if CHPL_AUX_FILESYS environment variable does
not contain the substring "lustre". In other words, only the run the test if
lustre support is compiled.

I realize this operator is not exactly intuitive, but it's no more or less
intuitive than the "contains" operator, <=.