Revise Docker infrastructure implementation code to find what should be fixed or implemented

[garagatyi]

Docker infrastructure implementation has a lot of things implemented to get POC.
We should revise it to find out whether there is anything that should be reimplemented or fixed and might influence SPI design.

[skabashnyuk]

Make sure these deprecated modules are reviewed

• che-core-api-machine-shared
• che-core-api-model-machine

[akorneta]

After the revision following issues were found:

• Workspace infrastructure termination issue;
• Machine config validation(circular dependencies) issue;
• Cleanup + define how to deal with exceptions inside WorkspaceRuntimes;
• Repair ssh access to the machine;
• Define output format rel;
• Rework snapshotting feature in accordance to master(workspace attributes + che properties).
• Rewrite WorkspaceLinksInjector in accordance to clients needs issue;
• Provide cleanup mechanism for docker infra isse;
• Provide workspace start interruption feature(in compliance with master branch);
• Write tests for infrastructure-docker module issue;
• Rewrite workspace API module tests;
• Get rid of RecipeDownloader + RecipeRetriever;

Cleanup commits:

8e1fe4b, 566a3df, 59aa09a, fd39d18, 1519136

[akorneta]

removed modules:

• che-core-api-machine-shared
• che-core-api-model-machine