Name should be trimmed

Hi,

I was setting ngx-avatar's name attribute to my user's Full Name. I get some errors like toUpper case is not a function. Then I realized ngx-avatar splitting the name by whitespace, and some of my users have whitespace in leading in their names. So an error occurs.

Maybe I am the one who should trim the name before saving to the db but also it can be added to the library.

Thank you 