switch pom to v1.73 and java 1.7

pom.xml

@@ -4,7 +4,7 @@
 
     <groupId>net.yacy</groupId>
     <artifactId>yacycore</artifactId>
-    <version>1.71</version>
+    <version>1.73</version>
     <packaging>jar</packaging>
     <description>YaCy - a Peer to Peer Web Search Engine</description>
     <name>YaCy</name>
@@ -31,10 +31,10 @@
 
     <properties>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
-        <maven.compiler.source>1.6</maven.compiler.source>
-        <maven.compiler.target>1.6</maven.compiler.target>
+        <maven.compiler.source>1.7</maven.compiler.source>
+        <maven.compiler.target>1.7</maven.compiler.target>
         <!-- the Solr version used in dependency section for all related dependencies -->
-        <solr.version>4.7.1</solr.version> 
+        <solr.version>4.8.0</solr.version> 
         
         <!-- properties used for filtering yacyBuildProperties.java -->       
         <REPL_DATE>${DSTAMP}</REPL_DATE>