JPA Dao implementation

[skabashnyuk]

Today to store information we using in memory storages which is backed as json files
during application suspend-startup. This approach is not scalable enough. To make
it more scalable, fault tolerant and concurrent we decided to move all our persistent storages to JPA based implementation. Potentially we will replace our in-memory implementation with JPA based. As JPA implementation we will take EclipseLink and h2 database.

See more
https://www.eclipse.org/eclipselink/
http://www.h2database.com/html/main.html

• UserService structural refactoring UserService structural refactoring #1846
• Create/Use TCK for UserDao Create/Use TCK for UserDao #1847
• Implement UserDao based on JPA Implement UserDao based on JPA #1811
• FactoryService structural refactoring FactoryService structural refactoring #1812
• Implementation of workspace service storage on JPA Implementation of workspace service storage on JPA #1813
• RecipeDao implementation on JPA RecipeDao implementation on JPA #1815
• StackDao implementation on JPA StackDao implementation on JPA #1795
• SnapshotDao implementation on JPA SnapshotDao implementation on JPA #1797
• Investigate strategies for cascade entities removing Investigate strategies for removing cascading entities #1803
• Create JPA based SshDao implementation Create JPA based SshDao implementation #1810
• Integrate JPA components/tools with Che Infrastructure Integrate JPA components/tools with Che Infrastructure #1807
• Don't store username as Workspace#namespace Don't store account name as Workspace#namespace #1950
• Migrate local json-based storage to jpa Migrate local json-based storage to jpa #2016
• User password stores/updates without encoding User password stores/updates without encoding #2136
• Merge model changes to JPA branch Merge model changes to JPA branch #2280

[bmicklea]

Added 5.0.0-M2 milestone to all issues completed at this stage.

[skabashnyuk]

Study how to make changes in model after migration to single database #2110
moved out of scope of this issue