Minor fixes and changes to cli plumbing commands (blame and diff-tree)

Minor edit to documentation
added raw version to show command
Made diff-tree use plumbing DiffTree operation instead of DiffOp

Adapted functional tests for diff-tree
Fixed issues in show command
Merge branch 'plumbing' of github.com:volaya/GeoGit into volaya-plumbing
Restore the use of checkParameter and newAnsi in Show.java
Set version to 0.6-SNAPSHOT
Add default logback.xml config file to be picked up by commands run outside a repository.
Set maven plugins version numbers.

This avoids the maven warning logs at build time complaining about
lack of version information in maven plugin declarations.
declare all depdendencies in the root pom.

All dependencies that were defined in module specific poms are now defined
in the dependencyManagement section of the root pom, and all dependency
versions are set as properties in the root pom's properties section.

This allows for an easier tracking of dependencies and versions.
Upgrade jcommander, jline, and mockito dependency numbers to their respective latests.
redirect java.util.logging loggers to slf4j even if not in a geogit directory
Make geogit-console log errors and not to fail when an exception is caught.
add missing handling of expected InvalidParameterException in geogit-console
fixed issue in Blame operation
fixed unflushed error message in console, from Diff-tree command
Merge pull request #321 from volaya/plumbing

Minor fixes and changes to cli plumbing commands (blame and diff-tree)