Finish importing ECS Beta 2 differences

[webmat]

This PR doesn't address the updates to HTTP, which are updated by #9645.

Changes:

• client/server, source/destination
  • Update each field set's definition
  • Add the .address field (except for source, which already had it)
• network: update definitions and examples wrt lowercase directive
• user_agent.original index is now keyword indexed (See Index user_agent.original, after all. ecs#262)
• Update ecs.version example <= this is of staggering importance! Just kidding

TODO

• make check fails, no wonder
• Fix test failures
• os here, or in a separate PR?
  • Separate PR

[webmat]

@andrewkroh I'm having problems with make update in Packetbeat. Does this ring a bell? fields_yml is equal to ., instead of being the path to the fields.yml file. Looked at the makefile, and everything looks good there, unless PWD starts with a . and a space. Doesn't seem likely.

Anyway, here's the result of one of my runs:

mage update
Generated fields.yml for packetbeat to /Users/mat/go/src/github.com/elastic/beats/packetbeat/fields.yml
Generated fields.yml for packetbeat to /Users/mat/go/src/github.com/elastic/beats/packetbeat/fields.yml
>> The index pattern was created under /Users/mat/go/src/github.com/elastic/beats/packetbeat/build/kibana/6/index-pattern/packetbeat.json
>> Building packetbeat.yml for linux/amd64
>> Building packetbeat.reference.yml for linux/amd64
>> Building packetbeat.docker.yml for linux/amd64
Traceback (most recent call last):
  File "/Users/mat/go/src/github.com/elastic/beats/libbeat/scripts/generate_fields_docs.py", line 169, in <module>
    with open(fields_yml) as f:
IOError: [Errno 21] Is a directory: '.'
Error: running "/Users/mat/go/src/github.com/elastic/beats/build/ve/darwin/bin/python /Users/mat/go/src/github.com/elastic/beats/libbeat/scripts/generate_fields_docs.py . packetbeat /Users/mat/go/src/github.com/elastic/beats --output_path /Users/mat/go/src/github.com/elastic/beats/packetbeat" failed with exit code 1
make: *** [update] Error 1

[ruflin]

@webmat Try running make clean and then make update

[webmat]

@ruflin Ah, that did it. Thanks!