no "If-None-Match: *" for PUT and debug output

"If-None-Match: *" for PUT only allows to create entries, not to update existing ones.
According to http://stackoverflow.com/questions/2111854/what-does-the-http-header-if-none-match-mean.
The current version of ownCloud implements it this way. Thus, this PR makes sogo-connector compatible with ownCloud again.