Add support for quoted local file path
Add support for quoted local file path

Addresses #68

Lyleo/OmniMarkupPreviewer,Lyleo/OmniMarkupPreviewer,timonwong/OmniMarkupPreviewer,Lyleo/OmniMarkupPreviewer,timonwong/OmniMarkupPreviewer,timonwong/OmniMarkupPreviewer,timonwong/OmniMarkupPreviewer,Lyleo/OmniMarkupPreviewer