Search and indexing toLowerCase() problem with Turkish regional settings 

Turkish language alphabet contains two distinct letters: lower case "i"
without the  dot and the capital "I" with the dot.
The upper case letter "I" is lower cased to letter "i" without the dot. 
The lower case letter "i" is upper cased to letter "I" with the dot.
This fact causes search problems with InstaSearch, where index and
search  facilities are carried out by converting strings to lower case.
Code usually don't contain Turkish alphabet specific letters. So when
converting to lower case a specific locale can be used.

This change converts all toLowerCase() calls to toLowerCase(Locale.ENGLISH)