Update README.md

Typo
Fixing the HttpSocket issue for CakePHP 2.3 https://github.com/dkullmann/CakePHP-Elastic-Search-DataSource/issues/11
Merge pull request #12 from burzum/bug/httpsocket-2.3

Fixing the HttpSocket issue for CakePHP 2.3 https://github.com/dkullmann...
Merge pull request #10 from sarce/patch-3

Typo
Minor fixes.
Allow searches without filters (using 'query' parameter).
In term() method:
If value is an array with multiple elements, use 'terms'.
If value is an array with one element, use 'term'.
New tests for searches.
New serverStatus() method in ElasticSource for checking server connection status.