Feature #72 - Manage tokens

[apanizo]

Description
This PR introduces the logic and UI changes which allow managing tokens on the default safe's view (Balances Tab).
Now we display selected tokens, and we include some features for filtering based on #73 description.

[apanizo]

Travis automatic deployment:
https://pr84--safereact.review.gnosisdev.com

Storybook book automatic deployment:
https://pr84--safereactstorybook.review.gnosisdev.com

[tschubotz]

Looks really smooth!

I just have 2 comments about the token search:

• Could we enable search by token name as well? i.e. e.g. searching for "Omis" would reveal the OMG token as well?
• Also, currently it's just a prefix search, right? so a search for "NO" would not return the GNO token. Could we change that to a "contain" search, i.e. the token is returned if the search term is a substring of token symbol or name?

[apanizo]

Travis automatic deployment:
https://pr84--safereact.review.gnosisdev.com

Storybook book automatic deployment:
https://pr84--safereactstorybook.review.gnosisdev.com

[apanizo]

Travis automatic deployment:
https://pr84--safereact.review.gnosisdev.com

Storybook book automatic deployment:
https://pr84--safereactstorybook.review.gnosisdev.com

[apanizo]

Thanks!!!

@tschubotz Changes submitted. Can you check again?

[apanizo]

Travis automatic deployment:
https://pr84--safereact.review.gnosisdev.com

Storybook book automatic deployment:
https://pr84--safereactstorybook.review.gnosisdev.com

[apanizo]

Travis automatic deployment:
https://pr84--safereact.review.gnosisdev.com

Storybook book automatic deployment:
https://pr84--safereactstorybook.review.gnosisdev.com

[apanizo]

Travis automatic deployment:
https://pr84--safereact.review.gnosisdev.com

Storybook book automatic deployment:
https://pr84--safereactstorybook.review.gnosisdev.com

[apanizo]

Travis automatic deployment:
https://pr84--safereact.review.gnosisdev.com

Storybook book automatic deployment:
https://pr84--safereactstorybook.review.gnosisdev.com

[tschubotz]

👍