Default to UTF-8 enabled locale

Currently, the locale is the POSIX default "C".
Some files in the moos tree, however, use UTF-8 characters, which can
cause applications to fail (notably, the SVN checkout & update process).
See themoos/essential-moos#15 for more context.

This commit changes the default to "C.UTF-8", enabling use of the
extended charset.

docker/moos-ivp/Dockerfile

@@ -23,6 +23,9 @@ WORKDIR "/home/moos"
 # Build Arguments
 ARG SVN_REV=HEAD
 
+# UTF-8 Encoding
+ENV LC_CTYPE="C.UTF-8"
+
 # Check-out the MOOS-IvP trunk
 RUN svn co -r "$SVN_REV" https://oceanai.mit.edu/svn/moos-ivp-aro/trunk /home/moos/moos-ivp