Allow Jython 2.5 failures on TravisCI

TODO - Work out if and how to fix Jython installation under TravisCI once again
Remove deprecated private function in SFF code
Mention Ion Torrent in SffIO docstring
Fix typo in error message
Fix typo in blastall wrapper
Add new Blast 2.2.27+ arguments to wrappers
Ignore new blastx arguments if testing with old BLAST+
BLAST 2.2.27+ dropped -frame_shift_penalty argument
Remove deprecated Bio.File.StringHandle and SGMLStripper

Also removes Bio.ParserSupport.SGMLStrippingConsumer
Remove centre setters, add explicit deprecation warning to getters.

i.e. This change makes the deprecated aliases read only, and adds an
explicit warning when reading the values. Previously only got a warning
on setting the value via the deprecated alias.
Clarify docstrings of deprecated BLAST functions.

No code changes, don't need TravisCI to test this: [ci skip]
Avoid ResourceWarning: unclosed file in these doctests
Close handle in this doctest
Remove the deprecated Seq object's data property
Remove duplicated section labels in Tutorial (in repeated Motifs text)
Downgrade Bio.Motif chapter to a section at the end of the Bio.motifs chapter
Fix a typo
Clarify docstring for obsolete Bio.Motif module
Explain Bio.motifs replaces Bio.Motif in its docstring
Update date in Tutorial