Fix utf-8 search with no results

The problem is in post processing of the search results:

unmatched_terms = [term for term in query
                        if term[1] not in term_matches]

query is [('text', 'inf\xc3\xb8rmation')]
term_matches is [u'inf\xf8rmation']

Since one is bytes and one is unicode, it is considered not matched.
The fix is to make them both unicode.

Fix #188 and #222
Merge pull request #223 from Connexions/fix-utf8-search

Fix utf-8 search with no results
Create plpython function "html_abstract" to transform cnxml abstract

Example usage:

`UPDATE abstracts SET html = html_abstract(abstract);`

MANUAL-UPGRADE: Need to create function (see schema.sql) in existing db
Merge pull request #225 from Connexions/transform-abstract

Create plpython function "html_abstract" to transform cnxml abstract
Normalize whitespace in search terms