Resolves T604 Fetch users posts if authenticated
This changes the 'posts' subcommand, previously 'list', to also list any
remote posts for the user if currently authenticated.
- adds DoFetchPosts to the api pkg which returns all the logged in users
- adds a RemotePost type to the api pkg which stores some of the return
information from DoFetchPosts for use in printing to stdout
- adds GetUserPosts to the api pkg which converts the incoming
writeas.Posts into the smaller RemotePost type
- adds getExcerpt which takes the incoming writeas.Post.Content and
returns a trimmed down excerpt of the content. Max 2 lines of 80 chars
and delimited by '...'
- changes CmdList from pkg commands to CmdListPosts which now writes out
any local and remote posts in simple formatted tables