enhanced base filter logic

new features  are

1) Many times i find myself wanting to apply OR logic on tags instead of AND and vice versa for exclude_tags
    this patch adds :include_any and :exclude_any booleans for inclusion/exclusion control.

2) Even more often I find myself wanting to filter based on event field names and not on tags, currently I'm forced to          do ugly stuff with lots of extra configuration to over come this limitation. So this patch ads :include_fields and :exclude_fields with same logic as :tags and :exlcude_tags  applied against existing event field names.

3) base filter can add/remove tags and can add fields with values  but cannot remove fields by fieldname
    this patch adds :remove_field option and deprecates :remove option of mutate filter

 4) also as discussed previously over irc - single value fields should be strings and not arrays then using :add_field