Add solr indexer to webapp

Thanks again @awoods for the dependencies fix. Now the fcrepo-jms-indexer-webapp works fine. 
This pull request 
1. add one missing httpmime lib into fcrepo-jms-indexer-core/pom.xml
2. add solr indexer into fcrepo-jms-indexer-webapp(To enable solr indexer, uncomment <ref bean="solrIndexer"/> inside Message Driven POJO in /fcrepo-jms-indexer-webapp/src/main/resources/spring/indexer-core.xml)

PS: the dependencies fix may cause JENA libs conflicts with latest fcrepo4 master(NOT solr dependence related) and cause fcrepo-jms-indexer-core compile fail as below:

WARNING] 
Dependency convergence error for org.apache.jena:jena-core:2.11.0 paths to dependency are:
+-org.fcrepo:fcrepo-jms-indexer-core:4.0.0-alpha-3-SNAPSHOT
  +-org.fcrepo:fcrepo-kernel:4.0.0-alpha-3-20131030.222157-73
    +-org.apache.jena:apache-jena-libs:2.11.0
      +-org.apache.jena:jena-tdb:0.10.1
        +-org.apache.jena:jena-arq:2.10.1
          +-org.apache.jena:jena-core:2.11.0
and
+-org.fcrepo:fcrepo-jms-indexer-core:4.0.0-alpha-3-SNAPSHOT
  +-org.fcrepo:fcrepo-kernel:4.0.0-alpha-3-20131030.222157-73
    +-org.apache.jena:apache-jena-libs:2.11.0
      +-org.apache.jena:jena-tdb:0.10.1
        +-org.apache.jena:jena-core:2.10.1
and
+-org.fcrepo:fcrepo-jms-indexer-core:4.0.0-alpha-3-SNAPSHOT
  +-org.apache.jena:jena-fuseki:0.2.7
    +-org.apache.jena:jena-core:2.10.1