Support the ability to download project zip file #373

* A new button is displayed on the project page to download the project zip file
* One can use curl to download the project zip file
curl -O -J -k --get --data "session.id=<session id>&project=<project nane>&download=true" http://<websever host>:<port>/manager
It's probably better to move the IOUtils.closeQuietly() to the `finally` block, and add
```
FileInputStream inStream = null;
OutputStream outStream = null;
```
before the `try` block.