initial commit of codebase

no parser yet
add composer support
return logoURI correctly
generate a guid if one is not given
rename Feed->getLink() to Feeg->getURI()
set guid to not isPermalink
add InvalidURIException
add comments to some Feed
check URI in Feed class for a valid URI
check URI in Enclosure class for a valid URI
check URI in Article class for a valid URI
add phpdoc to article class
reorder Feed parameters
change setID to be string in Article
add SerializationException
require only a title or description when generating RSS XML
rename getPublishedDate to getDatePublished
move pubDate above guid in RSSXML serialization
add language to feed
add setter for Feed fields