Remove API monospaced of the ClayIcon and add support to btn-monospaced in ClayButton

[matuzalemsteles]

This resolves #122.

• Remove API monospaced of the ClayIcon
• Add support the btn-monospaced in ClayButton
• Remove the monospaced pass to the icon, for dependent packages of the ClayIcon.

[carloslancha]

Just started reviewing :)

:octocat: Sent from GH.

[carloslancha]

LGTM