Strip carriage returns when computing config hash at check time.

At seeding time, the hash of the configuration file is computed using
Python code. The default behaviour of Python, when reading text files,
is to automatically translate CRLF line endings (such as those found in
text files originating from a Windows machine) into LF line endings
(normal line endings from the civilised world). This means that the
config hash is computed on a buffer that only contain LF line endings,
not CRLF line endings.

But at checking time, the hash of the configuration file is computed
using sha256sum, which takes the contents of the file as it is, without
any kind of mangling of the line endings.

On GNU/Linux and macOS, this all works fine, because the configuration
file only contains LF endings on those systems.

But on Windows, the default behaviour of Git, when checking out a
repository, is to write text files with CRLF line endings, therefore
causing the configuration file to have a sha256sum-computed hash that is
different from the Python-computed hash, and thus causing spurious
warnings from the ODK that the configuration file has changed since the
Makefile was last re-generated.

The fix is to forcefully strip all carriage returns (CR) from the
configuration file prior to computing its hash.

closes #1170

template/src/ontology/Makefile.jinja2

@@ -169,7 +169,7 @@ odkversion:
 {%- if project.config_hash %}
 .PHONY: config_check
 config_check:
-	@if [ "$$(sha256sum $(ONT)-odk.yaml | cut -c1-64)" = "$(CONFIG_HASH)" ]; then \
+	@if [ "$$(tr -d '\r' < $(ONT)-odk.yaml | sha256sum | cut -c1-64)" = "$(CONFIG_HASH)" ]; then \
 		echo "Repository is up-to-date." ; else \
 		echo "Your ODK configuration has changed since this Makefile was generated. You may need to run 'make update_repo'." ; fi
 {% endif %}