Add favicon image and upate .gitignore rules

[mitogh]

• What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)

Bug fix

• What is the current behavior? (You can also link to an open issue here)

Explained at #46

• What is the new behavior (if this is a feature change)?

Fixes #46

• Does this PR introduce a breaking change? (What changes might users need to make in their application due to this PR?)

None

• Other information:

This change allow to have a default favicon.ico image and update the .gitignore rules to track the new favicon.

Fixes #46

[adamf321]

@mitogh can you fix the ci errors?

[mitogh]

We need first https://github.com/moxie-leean/ng-web-app/pull/55, that PR solve this problem