Added table distinct and fixed links in joins

You are now able to get the distinct values of a table column:

$tripod->getDistinctTableColumnValues($tableSpecName, $fieldName);

=> array(
    'head'=>array(
        'count' => 3
     ),
     'results' =>array('Foo', 'Bar', 'Baz')
)

This release also fixes an issue where "value":"link" in a join definition in a tablespec would supply the URI of the top resource. It now supplies the URI of the current resource

Added counts functionality to tablespecs

You can now do limited counts in the tablespec:

{
  "counts" : [
    {
      "fieldName":"amazon_source_count",
      "property":"dct:isVersionOf",
      "regex":"/amazon/"
    }
  ] 
}

Unlike viewspec counts there can be no conditional filters that require a join, although limited filtering is available on the element to be counted via the optional regex.

This release also contains some minor tidying and also the start of documentation for the specifications.

Removed outdated references to SimpleGraph

This release is mis-named 0.4.1. Should have been 0.5.1.

Initial public release

Initial public release with MIT license. Over 0.4.6:

• For php53, up-to-date ARC dependancy via Composer
• Tidied up test data
• Quickguide via README.md