Cleaning check() warnings

- Re-ordered lines in ggplotly.R no longer considers "now" as part of the function, and cleans the warning:
checking Rd \usage sections ... WARNING
Documented arguments not in \usage in documentation object 'now':
'g' 'geom'

- Removed "required(RJSONIO)", cleans the following warning: 
library' or 'require' call to 'RJSONIO' which was already attached by Depends.
Please remove these calls from your code.

/cc @mkcor
/cc @xsaintmleux