Add timing for each sub_test call.

Register exit handler for sub_test python script that prints the elapsed
seconds from start up to exit (successful exit only). If sub_test is called
without CHPL_ONETEST, e.g. it is called on a directory, it will print a line
like the following when it is complete:

```
[Finished subtest "release/examples" - 16.330 seconds]
```

If sub_test is called with CHPL_ONETEST set, e.g. it is called on a specific
.chpl file, it will print a line like the following when it is complete:

```
[Finished subtest "release/examples/hello" - 2.711 seconds]
```

This will help developers do ad-hoc comparisons of nightly runs as needed. For
example, if a developer things a single test or new suite of tests is adding
significant time to the overall test time, it will be easy to find this line
and compare between two builds.

This is not meant to replace, or even enhance, compiler or runtime performance
tracking that already exists.
Remove a couple of debug lines
Merge branch 'master' of https://github.com/chapel-lang/chapel into add-timing-for-sub-test
Add support for detecting cray-xe and cray-xc platform.

Look for CLEinfo config file, read it, and inspect the NETWORK value. If it is
"gem", set platform to "cray-xe". If it is "ari", set platform to "cray-xc".

If the CLEinfo file does not exist, or if it does not contain a known NETWORK
value, default to the old platform logic.
fix typos in chpl_platform
Update README.cray to reflect platform detection on XC and XE.
Merge branch 'master' of github.com:chapel-lang/chapel into better-detect-cray-platform
Fix range
Update filename splitting based on review feedback.
Merge pull request #626 from thomasvandoren/add-timing-for-sub-test

Add timing for each sub_test call.

Register exit handler for sub_test python script that prints the elapsed
seconds from start up to exit (successful exit only). If sub_test is called
without CHPL_ONETEST, e.g. it is called on a directory, it will print a line
like the following when it is complete:

```
[Finished subtest "release/examples" - 16.330 seconds]
```

If sub_test is called with CHPL_ONETEST set, e.g. it is called on a specific
.chpl file, it will print a line like the following when it is complete:

```
[Finished subtest "release/examples/hello" - 2.711 seconds]
```

This will help developers do ad-hoc comparisons of nightly runs as needed. For
example, if a developer thinks a single test or new suite of tests is adding
significant time to the overall test time, it will be easy to find this line
and compare between two builds.

This is not meant to replace, or even enhance, compiler or runtime performance
tracking that already exists.
Merge pull request #630 from thomasvandoren/better-detect-cray-platform

Add support for detecting cray-xe and cray-xc platform.

Look for CLEinfo config file, read it, and inspect the NETWORK value. If it is
"gem", set platform to "cray-xe". If it is "ari", set platform to "cray-xc".

If the CLEinfo file does not exist, or if it does not contain a known NETWORK
value, default to the old platform logic.