Remove [] from seed tree files

[blakesweeney]

We should not use the tree names like '[]' in the seed tree FTP files. In newick format [] marks a comment (http://biowiki.org/wiki/index.php/Newick_Format, https://en.wikipedia.org/wiki/Newick_format). Because we use it as part of names it causes lots of problems for some parsers (some do not work, BioPython has incomplete data, etc). We should instead not use the names with [] to produce the seed files.