Release v0.4 for krep (2019-06-05)

It included the changes on tag CM-0.4 except the improvements and bugfixes on this branch:

Improvements:

• pki: use FileUtils.last_modified to get latest modified timestamp
• pki: use FileVersion.cmp to compare file version strings
• pki: provide several static methods for RepoImportSubcmd
• pki: support more xml elememnts for importing description
• pki: support to apply tag even without changes
• repo: handle option --offsite for sync
• repo: don't handle the heads like remotes/m which was created by git-repo
• repo: output upstream attribute when dumping an xml file
• repo: support option --ignore-new-project
• repo-import: add the new sub-command to import a directory for git-repo project
• subcmds: support option --head-pattern and --tag-pattern
• subcmds: support option --no-thin for git push

Bugfixes:

• pki: don't use git command in FileDiff.sync
• pki: update the order for directory sync and wash-out
• pki: don't execute import if target path is inexisted
• pki: update the behaviour for soft-linked files
• pki: secure the behaviour of option --offsite
• repo: output project name instead of subcommand name
• repo: update the way to indicate a project with its path and revision
• subcmds: correct option name for revision and head