use OurPkgVersion, not PkgVersion

This fixes warnings caused by interacting with the version number directly
Added docs explaining fallback.
update Changes
Added param handling for me method
Shortcut::Rows - create more shortcuts

Create two more shortcuts:
* has_rows: lighter way to check a resultset contain data than using
->count.
* limit: it's just an alias to "rows" one.
factor new methods into their own helpers
Test against 5.18 and 5.8 in TravisCI
Shortcut::Prefetch - create prefetch shortcut

A simple shortcut for the prefetch attr of search.
fix trailing whitespace
Added functionality and docs for free form order by clause.
move OrderBy magic to it's own shortcut
v2.018000

       - Add ::ResultSet::Shortcut::OrderByMagic (moltar)
       - Add ::ResultSet::Shortcut::Prefetch (Wallas Reis)
       - Add ::ResultSet::Shortcut::HasRows (Wallas Reis)
       - Add ::ResultSet::Shortcut::Limit (Wallas Reis)
       - make ::ResultSet::Me more flexible (moltar)
       - Fix some warnings (when using deprecated modules) (good catch Bill
         Mosely)
       - Fix lots of docs (moltar, Gregor Herrmann, mauke)