Prevent pushing to symbolic references
Added a Statistics web-api command.
Fixes errors in geogit-console

- Exception when closing console
- Eexception when starting console in a folder that is not a geogit repo
Fixed an issue which caused FindCommonAncestor to use too much memory.
Make osm import-history use the same feature types than osm import
Fixed an issue with LogOp with path filter.

LogOp was returning incorrect results when using a path filter without
the firstParent option set under certain conditions.
Remove dead code in PushManager and atomically update refs in EndPush.

org.geogit.web.api.commands.PushManager had a multimap keyked by remote IP
address whose values were supposedly all the object ids that have been
pushed, but they were never used (nobody calls PushManager.addObject() ), and
hance PushManager.alreadyPushed() is useless.

Removed all the dead code and made it so that PushManager.connectionSucceeded(...)
uses a geogit transaction to atomically update all the refs.
Updated javadocs for PushManager
Merge branch 'statisticsOp' of github.com:kelseyishmael/GeoGit into kelseyishmael-statisticsOp

Conflicts:
	src/web/api/src/main/java/org/geogit/web/api/CommandBuilder.java
	src/web/api/src/main/java/org/geogit/web/api/ResponseWriter.java
use CamelCase for inner class name
Merge pull request #724 from jdgarrett/find-common-ancestor-memory

Fixed an issue which caused FindCommonAncestor to use too much memory.
Merge branch 'log-op-fix' of github.com:jdgarrett/GeoGit into jdgarrett-log-op-fix
Use ObjectId.isNull() instead of ObjectId.equals(ObjectId.NULL) for covnenience
Merge pull request #719 from volaya/console_fixes

Fixes errors in geogit-console
Merge pull request #705 from volaya/push_symbolic

Prevent pushing to symbolic references
Allow defining mandatory tags in OSM mappings
some typo and grammar fixes to osm.rst