Tweaked readme file

- added some small fixes
- added unittests

Conflicts:
	library/Solarium/Exception/HttpException.php

Add body to HttpException (if available). Bad Request 400 is simply not sufficient to debug problems

Update composer.json

Use same PHP version as for Symfony component to match its requirements.

Conflicts:
	library/Solarium/Client/ResponseParser/Select/Component/FacetSet.php
	library/Solarium/QueryType/Select/Query/Component/FacetSet.php

* Since some Solr setups might configure their facets in
  solrconfig.xml, this option allows you to tell the
  response builder to construct the facet response from
  what is actually returned in the response rather than having
  to define it in the query object first.

Conflicts:
	library/Solarium/QueryType/Select/ResponseParser/Component/FacetSet.php
	library/Solarium/QueryType/Select/Result/Facet/Range.php
	tests/Solarium/Tests/QueryType/Select/Result/Facet/RangeTest.php

Conflicts:
	library/Solarium/QueryType/Select/Query/Query.php

[composer] Loosen symfony/event-dispatcher constraint

* Some Solr configurations have complex queries
  defined in solrconfig.xml with custom parameters,
  because of this, you might not always want the
  'q' parameter sent, this patch allows you to set
  'query' to NULL so that when you do it prevents
  'q' from being sent at all.