Add user apps Kconfig for settings

[louisom]

In this moment, build system will build all program in folder user/apps, but this may cause unexpected effect, for example, let kdb unusable in UART.

So, we can add a new kconfig file for apps like test cases or real user program like pingpong, and thus rename menu title from "Test Case" to "User Space".

And add submenu "Apps" and "Test Cases" for now.

The structure look like this:

• User Space
  • [ ] Compile with user apps
  • Apps
  • Test Cases

[louisom]

It seems that travis CI broke by new settings....

$ build/host/conf --silentoldconfig build/host/Config.in
*
* Restart config...
*
*
* User Space
*
Compile with user apps (USER_APPS_INCLUDE) [N/y/?] (NEW) 

[jserv]

Cc. @georgekang

[jserv]

user/apps is not a folder. It is a "directory" instead.

[jserv]

@grapherd, You have to update Travis-CI configurations right after new options are introduced.

[louisom]

I found that there have still some problem need to be clear.

I can only success to see kdb when first make defconfig then disable USER_APPS_ENABLED.

If I first disable USER_APPS_ENABLED then make flash, it won't appear kdb, but only == on screen.

[jserv]

I expect there are only two commis: one is Kconfig changes, and another is Travis-CI specific update.

[louisom]

@jserv fixed, commit change to Add user apps kconfig and update board defconfig