themes: make 'agnoster copy' back into 'agnoster'

registry: add pbcopy plugin

describe without ruby

no dependency on ruby & a little quicker. all credit to @derekstavis for the
cool regexs

describe works on installed packages

also modified list_db_packages to return all packages by default, but with a
skip_installed to skip listing installed packages

Add updated tab plugin

Add bundler package

Do not convert `$HOME` when installing omf.

Keep `$HOME` variable inside `config.fish` when installing oh my fish
instead of converting it to its content.

autocomplete help

added brew & sublime packages

Adding maven plugin

implements help for commands

Fix #545: Remove custom packages and themes

Remove function was not deleting packages and themes from the OMF_CONFIG
folder.

Update repo for local-config plugin

Since they're plugins again :P

describe command

to easily see from commandline what each package does via their descriptions
on github

registry: add foreign-env plugin

Update rbenv plugin git location

registry: add title plugin

Reference #517 Add default theme to database

cd command

Jump around Oh My Fish packages and themes using `omf cd <name>`. If no
<name> is specified, jump to oh my fish root folder.