JGit 3.3 New and Noteworthy

# Features

- Add symlink support to JGit (Java 7 only, including newer Windows versions provided the user has SeCreateSymbolicLinkPrivilege).
- Abstraction for HTTP connections and alternate implementation using Apache HttpClient
- Use branch.<x>.mergeoptions and merge.ff as defaults for merging
- Support fetch.prune and remote.<name>.prune to set prune mode when fetching
- Add git checkout --orphan implementation
- Suppport the GIT_CONFIG_NOSYSTEM environment variable
- Include entries for directories for archive command
- Prepend a specified prefix to all entry filenames for archive command
- Add delete support to FS
- Ban dangerous ref names on Windows
- Allow programmatic remote configuration for PullCommand

## Command Line

- Add option --millis / -m to debug-show-dir-cache command

## Performance Improvements

- Use fileAttributes to get more attributes in one go on Java 7
- Non-Fast-Forward Ref-Updates: Omit isMergedInto() calls

## Build and Release Engineering

- Update Kepler target platform to use Kepler SR2 orbit R-build
- Update Luna target platform to use Luna M5 orbit repository
- Update com.jcraft.jsch to 0.1.50
- Update commons-compress to 1.6
- Upgrade javaewah to version 0.7.9