Review Request 65246: Added download button for master and agent logs in Web UI.

[Armand Grillet]

-----------------------------------------------------------
This is an automatically generated e-mail. To reply, visit:
https://reviews.apache.org/r/65246/
-----------------------------------------------------------

Review request for mesos, Benjamin Mahler and Vinod Kone.


Bugs: MESOS-8454
    https://issues.apache.org/jira/browse/MESOS-8454


Repository: mesos


Description
-------

See summary.


Diffs
-----

  src/webui/master/static/agent.html 908d01d1d28f2a4fc595b581fa16515c5be1410a 
  src/webui/master/static/home.html df3eef61eb9564dbdfc3d138ecfd18e85f747f11 
  src/webui/master/static/js/controllers.js 
59665869dbea77c00740e42f2590473181dfe2fe 


Diff: https://reviews.apache.org/r/65246/diff/1/


Testing
-------

Created an High Availability Mode Mesos cluster locally:

```
$ zkServer start
$ bash mesos-master.sh --port='5061' --zk='zk://127.0.0.1:2181/mesos' 
--work_dir='/tmp/master1' --quorum=1 
--webui_dir='/Users/Armand/Code/apache-mesos/src/webui' 
--log_dir='/tmp/master1-log'
$ bash mesos-master.sh --port='5062' --zk='zk://127.0.0.1:2181/mesos' 
--work_dir='/tmp/master2' --quorum=1 
--webui_dir='/Users/Armand/Code/apache-mesos/src/webui' 
--log_dir='/tmp/master2-log'
$ bash mesos-agent.sh --port='5051' --master='zk://127.0.0.1:2181/mesos' 
--work_dir='/tmp/agent1' --log_dir='/tmp/agent1-log'
```
Tested the download and streaming features on the home and agents Web UI 
endpoints, from both `http://localhost:5061/` and `http://localhost:5062/`.

New UI:
![New logs button](https://i.imgur.com/vo9mXT6.png)


Thanks,

Armand Grillet