Bump pom to 1.0.6-SNAPSHOT for git-client-plugin

git-client-plugin changeset "Handle merge failure" required for
"Fix serialization to slave" to pass unit tests
Merge pull request #151 from timsnyder/master

Bump git-client-plugin to 1.0.6-SNAPSHOT
When two MatrixRun runs on different threads, run[0]++ isn't safe.

... because there's no barrier
Using the checkoutBranch method