Escape values that containt slash (/) at the begining - SOLR 4 intruduce...

SOLR 4 introduced new query feature - regular expressions, which breaks existing code.

In SOLR3:
text:/value/a

would search for "/value/a"

In SOLR4:
text:/value/a
means search using regular expression, which makes query invalid.

This patch changes serialization when slash is in the beginining it is automatically quoted to ensure backward compatibility.

Why:
I reckon than in future SolrNet versions there would be different syntax for handling regex queries (like Query.Field("text").Regex()), so it is ok, to change serialization of existing syntax.

...d regex queries and this commit is not introducing this functinoality but prevent breaking old code.