fix version conflicts of old jackson
1) Update to mmx build of jackson 2.1 branch to get bug-fix for jackson-databind #167
1) Fix alert sent from line DruidMasterBalancer:71 to not include all of the segments that a server is holding
[maven-release-plugin] prepare release druid-0.2.8
[maven-release-plugin] prepare for next development iteration
1) Fix bug in index converter when column has cardinality 0
Merge branch 'master' of github.com:metamx/druid
IndexMergerTest: Empty column test
[maven-release-plugin] prepare release druid-0.2.9
[maven-release-plugin] prepare for next development iteration
Additional fix for columns with cardinality 0
Merge pull request #88 from metamx/8to9-empty-column

Additional fix for columns with cardinality 0
1) Remove stray import of java.util.List
merge master