Support case insensitive fieldnames from solr

[juarezr]

Today mixed case field return null value instead. For example:

<field name="id" type="string" indexed="true" stored="true"  />
<field name="clientId" type="string" indexed="true" stored="true"  required="true"/>
<field name="ownerId" type="string" indexed="true" stored="true" required="true"/>

Using the following query:

SELECT id, clientId, ownerId from my_solr_table limit 1

will return the values:

• abcefg
• null
• null