Rename the installed executable to glcr

[aspiers]

Eventually, this will probably be taken care of by setup.py or similar. For
now, it's better not to rename the source file, because that would break every
existing pull request.

Closes #30 and closes #47.

[basak]

This would break the other examples in the same README.md. Can we hold and commit all necessary changes needed for the rename all at once (not necessarily in the same commit, but in time, so users are most likely to continue seeing everything consistent)?

[basak]

I'm not sure what "all changes" means exactly - are there self-references anywhere else in this repo? Also, maybe we could prepare a pull request for Joey for git-annex at the same time? He probably won't want to commit the rename until we have done so, but maybe we could commit the rename here and send a pre-prepared pull request to Joey as soon as it's done.

My concern is just that it doesn't end up half done because we started it and then got distracted by other priorities (as often happens).

[aspiers]

Oops, you're right. Updated the commit with the other references.

Good idea about sending a patch to Joey too, although he doesn't accept pull requests AFAIK.