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
Add transform module content function to be used in postgres

For example,

`SELECT html_content(encode(file, 'escape')::text) FROM files`

to get the cnxml in "file" transformed to html,
but this does not add any files to the database.

MANUAL-UPGRADE: add a function (see schema.sql) to existing db
Change cgi.parse_qs to urlparse.parse_qs as it's deprecated

cgi.parse_qs has been copied to urlparse.parse_qs
(https://docs.python.org/2/library/urlparse.html#urlparse.parse_qs)
Add pagination to search results, default 20 results per page

For example, if you search for `q=introduction`, you'll get 5 results.
You can force pagination by searching for `q=introduction&per_page=3`.
You will get 3 result items instead of 5 and you can fetch the remaining
2 items by doing `q=introduction&per_page=3&page=2`.

Search results `query` will now contain the `per_page` value and `page`
number.  Search results will only return 20 `items` by default.
Everything else in the search results remain unchanged.
Merge pull request #227 from Connexions/search-pagination

Search pagination
Merge pull request #226 from Connexions/transform-module-content

Add transform module content function to be used in postgres
determine recencey based on data, not clock
Remove stopwords from wildcard search terms

Stopwords are not removed from specific search fields and if the search
only consists of stopwords

The list of English common words was downloaded from
http://www.textfixer.com/resources/common-english-words.txt
Merge pull request #228 from Connexions/hits-recent-fix

determine recencey based on data, not clock
Merge pull request #229 from Connexions/remove-stopwords

Remove stopwords from wildcard search terms
Rename "Collection" to "Book" and "Module" to "Page"

This changes the name of the search filter.

Also changed mediaType to "application/vnd.org.cnx.collection" and
"application/vnd.org.cnx.module"

Close #230
Merge pull request #231 from Connexions/rename-module-and-collection

Rename "Collection" to "Book" and "Module" to "Page"
Always return all the books first in search results
don't even go to the DB for 0 wiught terms
Merge pull request #234 from Connexions/search-returns-books-first

Always return all the books first in search results
ignore all non-quoted stop w words
add non-zero weight for parentauthor test
Label with format items of the search query.
Adjust format (pep8)