Draft of concurrency
Move concurrency.md to _drafts folder.
Update concurrency.md
Add information about processes and threads
Add information about invoking scripts.
Update concurrency.md
Add information about thread state
Create testing.md
Update testing.md
Add additional definition
Update testing.md
Create java-generics.md
Add purposes of using generics
Add additional information of generics type
Add definition of type parameter and type argument
Add generic method part
Add generic restriction
Adding type inference and type erasure part
Add small fixes
Merge pull request #2 from stavytskyi/java_generics

Java generics