Provide config method to update tracker

#11 thanks @adlenafane !

added nonInteraction option

#8 - Feat(event) - added nonInteraction option, thanks @adlenafane

let ga determine the default value of pageview if payload.[KEYS] is not assigned

#9 - let ga determine the default value of pageview if payload.[KEYS] is not assigned, thanks @hero78119

add pageview location support

#6 - add location parameter into the pageview function, thanks @adlenafane

fix function scope issue

#5 - fix function scope issue generated by #4 and #3

some minor fix

#4 - based on #3 some minor fix,thanks @hero78119

support ga customized tracker

#3 - support ga customized tracker and more commands, thanks @hero78119