[#85179216] implicit and explicit conversions of PGit::Command instance
to hash
[#85179216] PGit::CurrentProject implements #to_h and #to_hash
[#85179216] a command instance can now save if there is only one project
in the configuration file
[#85179216] changed CurrentProject#pwd to #path

- looks more like the configuration yaml
[#85179216] not expand_path anymore to make refactoring easier
[#85179216] implemented CurrentProject#commands=
[#85179216] simplified call to path
[#85179216] implemented configuration#projects=()
[#85179216] implemented CurrentProject#save

- uses Configuration#save
[#85179216] first pass on "pgit command add"

- adds the command into the current projects' command hash
- overwrites existing command if it has the same name
- requires '--name' and '--steps'

TODO:
- throw warning if command exists
[#85179216] as of right now, pgit command -x only takes one argument
[#85179216] removed feature-comments
[#85179216] PGit::CurrentProject::Command#add

- complains if the command already exists
[#85179216] PGit::CurrentProject::Command#add

- shows successful message if the command did not exist before