[Integrated] RFR: cli: add trees command

[Erik Helin]

Changeset: 8d9b6e98
Author:    Erik Helin <ehelin at openjdk.org>
Date:      2020-04-24 11:26:24 +0000
URL:       https://git.openjdk.java.net/skara/commit/8d9b6e98

cli: add trees command

Reviewed-by: rwestberg

! cli/build.gradle
! cli/src/main/java/org/openjdk/skara/cli/GitSkara.java
+ cli/src/main/java/org/openjdk/skara/cli/GitTrees.java
! skara.gitconfig
! skara.py