Prepare for gem release

Add naive adjudication and adjudicated object
Add diplo module adjudicate method
Update gemspec file
Add errors class/file

Squashed commit of the following:

commit f65d443af3788baf26bd8a8acc1ffedbd0ec809f
    Add Homepage to gemspec
commit 315bfa8caada3d73ebdecc90630d63d7d2ed9e14
    Diplo module adjudicates (randomly)
commit c132f7bd30a248846d962758e0f0078b0082e4a2
    Continue work on Diplo.adjudicate()
commit 795b6fe608fca44fcc1181e373350a6b99ada63f
    Add DiploError
commit 7b19211ef0fabe158ade2d6e88c289c9e13618b0
    WIP Add interface to gem (commented in diplo.rb)
commit ea7c05a2951b3d1ec92604f3c21835b7101d6011
    Add Adjudicated class and spec
commit 228af66a15e728ca693c576b819bd0d2f85086b0
    WIP Connect Diplo module to Adjudicator