Don't hardcode pandoc version in osx/distribution.xml.

Instead, create it from a template, distribution.xml.in.

make_osx_package.sh

@@ -61,6 +61,8 @@ echo Creating OSX package...
 # remove old package first
 rm -rf $BASE.pkg
 
+sed -e "s/PANDOCVERSION/$VERSION/" osx/distribution.xml.in > osx/distribution.xml
+
 pkgbuild --root $DIST/pandoc --identifier net.johnmacfarlane.pandoc --version 1.13 --ownership recommended $DIST/pandoc.pkg
 productbuild --distribution osx/distribution.xml --resources $DIST/Resources --package-path $DIST --version $VERSION --sign "${DEVELOPER_ID_INSTALLER}" $BASE-osx.pkg
 

osx/distribution.xml.in

@@ -11,7 +11,7 @@
     <options hostArchitectures="x86_64" />
     <!-- List all component packages -->
     <pkg-ref id="net.johnmacfarlane.pandoc"
-             version="1.17"
+             version="PANDOCVERSION"
              auth="root">pandoc.pkg</pkg-ref>
     <!-- List them again here. They can now be organized
          as a hierarchy if you want. -->