Add script to prepend copyright with license info to source files.

The util/buildRelease/add_license_to_sources.py script accepts a list of files,
detects the type of comment for each one, and then prepends a comment including
the copyright with license info. The content is stored in a separate file to
make versioning/history easier.
Prepend comment to all sources with copyright and license information.

This uses the new `util/buildRelease/add_license_to_sources.py` script. I ran
this code in bash to tag all of these files:

```bash
find "compiler runtime make modules" \
    -name Make\* -o \
    -name \*.c -o \
    -name \*.chpl -o \
    -name \*.cpp -o \
    -name \*.g -o \
    -name \*.h -o \
    -name \*.lex -o \
    -name \*.y -o \
    -name \*.ypp | \
    grep -v compiler/parser/chapel.tab.h | \
    grep -v compiler/parser/chapel.tab.cpp | \
    xargs ./util/buildRelease/add_license_to_sources.py

find . -maxdepth 1 \
    -name Make\* | \
    xargs ./util/buildRelease/add_license_to_sources.py
```

Those find calls were derived from the existing `make/Makefile.release`, which
is called from `util/buildRelease/gen_release`. I did not include the `*.g`
files because none such files exist in the repository.
Remove make/Makefile.release and do not call it from gen_release.

This is no longer needed, since the sources have the comments when they are
checked into the repo.