corplist: remove extra download links

[Ansa211]

In current corplist.xml, Summa theologiae does not have any "repo" parameter. So no download link should be shown in corplist:

<corpus ident="summa_la_a" keyboard_lang="en" sentence_struct="s" features="morphology, syntax" access="anonymous"  parallel="default">
        <metadata>
            <keywords>
                <item>parallel</item>
                <item>Summa</item>
                <item>la</item>
                <item>morphology</item>
                <item>syntax</item>
                <item>current</item>
            </keywords>
        </metadata>
    </corpus>
    <corpus ident="summa_cs_a" keyboard_lang="cs" sentence_struct="s" features="morphology, syntax" access="anonymous"  parallel="complement">
        <metadata>
            <keywords>
                <item>parallel</item>
                <item>Summa</item>
                <item>cs</item>
                <item>morphology</item>
                <item>syntax</item>
                <item>current</item>
            </keywords>
        </metadata>
    </corpus>
    <corpus ident="summa_en_a" keyboard_lang="en" sentence_struct="s" features="morphology, syntax" access="anonymous"  parallel="complement">
        <metadata>
            <keywords>
                <item>parallel</item>
                <item>Summa</item>
                <item>en</item>
                <item>morphology</item>
                <item>syntax</item>
                <item>current</item>
            </keywords>
        </metadata>
    </corpus>

[Ansa211]

This is a duplicate of #132 Judging by the comments, the patch is available in the origin/kontext-dev branch but has not been merged into origin/master