Removed hard-coded patch for Solr 5.0 on ranking boost function

The current default boost function
(`recip(ms(NOW,last_modified),3.16e-11,1,1)`) for the Date ranking
profile is indeed working fine.
What can trigger the error `unexpected docvalues type NUMERIC for field
'last_modified'` is the previous default boost function (quite old now)
or any custom one using the Solr `ord` or `rord` functions on the
last_modified field.
Then the problem was that the migration code in the Switchboard supposed
to detect the old date boost function was incorrect (one trailing right
parenthesis in excess), so the deprecated function remained.

This fixes issue #169.

source/net/yacy/cora/federate/solr/Ranking.java

@@ -177,7 +177,6 @@ public class Ranking {
      * @return
      */
     public String getBoostFunction() {
-        if (this.boostFunction.contains("last_modified")) return ""; // since solr 5.0 this does not work any more
         return this.boostFunction;
     }
     

source/net/yacy/search/Switchboard.java

@@ -554,7 +554,7 @@ public final class Switchboard extends serverSwitch {
             // apply some hard-coded patches for earlier experiments we do not want any more
             if (bf.equals("product(recip(rord(last_modified),1,1000,1000),div(product(log(product(references_external_i,references_exthosts_i)),div(references_internal_i,host_extent_i)),add(crawldepth_i,1)))") ||
                 bf.equals("scale(cr_host_norm_i,1,20)")) bf = "";
-            if (bf.equals("recip(rord(last_modified),1,1000,1000))")) bf = "recip(ms(NOW,last_modified),3.16e-11,1,1)"; // that was an outdated date boost that did not work well
+            if (bf.equals("recip(rord(last_modified),1,1000,1000)")) bf = "recip(ms(NOW,last_modified),3.16e-11,1,1)"; // that was an outdated date boost that did not work well
             if (i == 0 && bq.equals("fuzzy_signature_unique_b:true^100000.0")) bq = "crawldepth_i:0^0.8 crawldepth_i:1^0.4";
             if (bq.equals("crawldepth_i:0^0.8 crawldepth_i:1^0.4")) bq = "crawldepth_i:0^0.8\ncrawldepth_i:1^0.4"; // Fix issue with multiple Boost Queries
             if (boosts.equals("url_paths_sxt^1000.0,synonyms_sxt^1.0,title^10000.0,text_t^2.0,h1_txt^1000.0,h2_txt^100.0,host_organization_s^100000.0")) boosts = "url_paths_sxt^3.0,synonyms_sxt^0.5,title^5.0,text_t^1.0,host_s^6.0,h1_txt^5.0,url_file_name_tokens_t^4.0,h2_txt^2.0";