Rename the installed executable to glcr

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.

README.md

@@ -127,11 +127,11 @@ Then clone this repository:
 
 and either, for all users:
 
-    sudo ln -s $PWD/glacier-cli/glacier.py /usr/local/bin/glacier
+    sudo ln -s $PWD/glacier-cli/glacier.py /usr/local/bin/glcr
 
 or for just yourself, if you have `~/bin` in your path:
 
-    ln -s $PWD/glacier-cli/glacier.py ~/bin/glacier
+    ln -s $PWD/glacier-cli/glacier.py ~/bin/glcr
 
 Integration with git-annex
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