Add nested unordered list items

[Yoruba]

Added support for unordered list items. See link for issue.

Maybe the code is write to defensive.
Normally there is always a depth and unorderedListItemCustomStyleBullet.
It was added to pass the test.

[coveralls]

Coverage increased (+1.8%) to 95.925% when pulling 3d43b5f on Yoruba:master into 93df7cb on globocom:master.

[Canedo]

Hey @Yoruba !

I updated all devDependencies and fixed some CI and automatization on the project.

But with your PR our coverage dropped a little bit. Do you mind trying to create a few unit test to check your logic on these files?

https://github.com/globocom/react-native-draftjs-render/pull/31/files/f7f87ad109eb7ebe3f06a2cce6c5db6a7c4f5c28..3e881a679ee13a2d45b2deeb2e06a7b075b6f869#diff-9ab480e59fc715571c0ccc187389685b

https://github.com/globocom/react-native-draftjs-render/pull/31/files/f7f87ad109eb7ebe3f06a2cce6c5db6a7c4f5c28..3e881a679ee13a2d45b2deeb2e06a7b075b6f869#diff-499a02caa53655ba5d4e742ebad4fed3

https://github.com/globocom/react-native-draftjs-render/pull/31/files/f7f87ad109eb7ebe3f06a2cce6c5db6a7c4f5c28..3e881a679ee13a2d45b2deeb2e06a7b075b6f869#diff-3734209372a61119ea09fecad32c76d4

[Canedo]

Hey @Yoruba . It's looking great!

I'll release a new version this week with your PR. I'll let you know when i'm done.