*Motivation*

Bump the development version to 2.6.0-SNAPSHOT

* Upgrade dependencies for security fixes

* Use guava 18 for jclouds-shaded

* Fix the guava version for HDFS tiered storage component

* Rollback guava to 25.1 since there are API breaking changes

* Rollback to Maven 3.0.5 which has the fix for sec issue

* Fixed Jetty SslContextFactory creation

* Roll back to 9.4.20.v20190813

### Motivation

Shade all transitive dependencies in module jcloud-shaded.  This is needed to get offloaders working nicely with presto and pulsar in the pulsar presto plugin.  I will have a subsequent PR for that.

Not sure why we don't shade all transitive dependencies for jcloud anyways like we do for other modules.

### Motivation

This is a part of tracking work in #2164. currently we use a snapshot version of jclouds for some jclouds bug fix. This change will remove the snapshot version and use latest release 2.1.1.

### Modifications

update pom.xml to use 2.1.1

### Result

tired storage ut should pass

This is the second part to support `Google Cloud Storage` offload. 
It aims to replace "s3 client" api with "jclouds" api, and make sure unit test and integration test passed.
There will be a following change to add `Google Cloud Storage` support and related test.

change:
replace `s3client` api with `jclouds` related api in `S3ManagedLedgerOffloader`

Master Issue: #2067 

Signed-off-by: NSijie Guo <sijie@apache.org>

* Used shaded version of protobuf-2.4.1 internally, to coexist with components using proto3

* 2.1 parent pom

* Add proto3 dependency back since before it was relying on the proto2 dependency

* Fixed dependency

* Updates headers with ASF source files header

* change license to additional files