Updated test templates

[c-vetter]

Makes the default tests run with success result instead of error.

Also, while I was at it, I removed the mocking due to the now-closed jest/react-dom issue

Before

yarn test

yarn test v0.24.6
$ grommet check
[grommet:check]: Running Javascript linting...
[grommet:check]: Running SCSS linting...
[grommet:check]: Running Tests...
 FAIL  __tests__\components\NavSidebar-test.js
  ● Test suite failed to run

    TypeError: (0 , _reactRouter.createMemoryHistory) is not a function

      at Object.<anonymous> (__tests__\components\NavSidebar-test.js:18:949)
      at process._tickCallback (internal\process\next_tick.js:109:7)


=============================== Coverage summary ===============================
Statements   : 0% ( 0/570 )
Branches     : 0% ( 0/392 )
Functions    : 0% ( 0/171 )
Lines        : 0% ( 0/243 )
================================================================================
Test Suites: 1 failed, 1 total
Tests:       0 total
Snapshots:   0 total
Time:        4.699s
Ran all test suites.
[grommet:check]: failed
Tests Failed
error Command failed with exit code 1.

After

yarn test

yarn test v0.24.6
$ grommet check
[grommet:check]: Running Javascript linting...
[grommet:check]: Running SCSS linting...
[grommet:check]: Running Tests...
 PASS  __tests__\components\NavSidebar-test.js
  √ NavSidebar renders (9ms)


=============================== Coverage summary ===============================
Statements   : 6.52% ( 36/552 )
Branches     : 1.19% ( 4/336 )
Functions    : 1.8% ( 3/167 )
Lines        : 11.04% ( 35/317 )
================================================================================
Snapshot Summary
 › 1 snapshot written in 1 test suite.

Test Suites: 1 passed, 1 total
Tests:       1 passed, 1 total
Snapshots:   1 added, 1 total
Time:        4.31s
Ran all test suites.
[grommet:check]: success
✨ 6.63 s
Done in 9.17s.

Steps to Reproduce

1. grommet new test-app, accept defaults
2. cd test-app
3. yarn test

Environment

• Grommet version: 1.4.0
• Operating System and version (desktop or mobile): Windows 7 Ultimate (desktop)
• yarn version: 0.24.6
• node version: 6.10.3
• React version: 15.5.4
• React-Router version: 4.1.1

[alansouzati]

thanks for your contribution