Change structure of search result limits

This change will probably make it faster for webview to display the
search filters.
need tag join whenever subject searched
implement subject matching as an SQL limit w/ group by and having
stabilize the order of results sets w/ runs of identical weights
Merge pull request #147 from karenc/new-search-result-limits-format

Change structure of search result limits
Change "author" to "authorID" in search result limit
add osx development instructions and notes
Merge pull request #150 from karenc/fix-search-limit

Change "author" to "authorID" in search result limit
Fixes Connexions/cnx-upgrade#21
Fixes the resolver to parse reference strings by possible type.
This revises the string parsing to use a regex that attempts to recognize paths to resources and internal document references.
only message if there are bad refs
fix_reference_urls returns bad refs as well
Merge pull request #151 from Connexions/osx-documentation

add osx development instructions and notes
Merge pull request #149 from Connexions/limit-only-tests

Limit only subject implementation
load DTDs in order to expand entities
test entity expansion
don't force use of our cnxml/DTD packages, just fetch them from cnx.org
need to explicitly turn on network lookup
Merge pull request #153 from Connexions/load-and-resolve-entities

load DTDs in order to expand entities
Removes collection transforms.