Use Symver for releases

Ok, releasing using datetimes was extremely bad.

Author: syndbg

libexec/goenv---version

@@ -12,7 +12,7 @@
 set -e
 [ -n "$GOENV_DEBUG" ] && set -x
 
-version="20160424"
+version="1.0.0"
 git_revision=""
 
 if cd "${BASH_SOURCE%/*}" 2>/dev/null && git remote -v 2>/dev/null | grep -q pyenv; then