fix debug override

add description to readme
allow subdomains and multiple top-level domains

adds config options: domain_name and allow_linker
fix options detection from hash
Merge branch 'master' into features/domain_name_and_allow_linker

Conflicts:
	lib/middleman-google-analytics/extension.rb
fix options attributes
Merge pull request #9 from kpricorn/features/domain_name_and_allow_linker

Features/domain name and allow linker