Support for Abandoned in Packages

Added parsing for abandoned property into the CompletePackage Object.
Abandoned support in `show`

Executing `composer show` on an abandoned package displays the warnings for package status.
Abandoned packages support

Added warning to the installer process.
If any installed packages are flagged, the user will get a warning at the end
of the install/update process.
PR Review

- reverted comma removal
- made getReplacementPackage consistent
- removed abandoned flag if false
Merge pull request #3325 from rdohms/implementing-abandoned-packages

Abandoned Package Warnings