Correct meta viewport content syntax

The viewport content value should be comma-delimited, and it should not
have a final semicolon.

Chrome 31 gives warning messages about the current implementation:

    The value "1.0;" for key "initial-scale" was truncated to its numeric prefix.
    The value "1.0;" for key "maximum-scale" was truncated to its numeric prefix.
    The value "0;" for key "user-scalable" was truncated to its numeric prefix.
    Error parsing a meta element's content: ';' is not a valid key-value pair separator. Please use ',' instead.

This change fixes all 4 of those warnings.

Alex Gibson covers the proper syntax in ["Make sure to use correct meta
viewport syntax"][1]

[1] http://alxgbsn.co.uk/2011/11/23/make-sure-to-use-correct-meta-viewport-syntax/
Merge pull request #256 from ssorallen/master

Correct meta viewport content syntax