Create PY2 CMSCouchapp spec; remove old couchapp/restkit specs

[amaltaro]

Changes required by: dmwm/WMCore#10485

Summary of changes is:

• created a new python2 spec file for the CMSCouchapp third-party library (from https://github.com/amaltaro/couchapp)
• replace the old couchapp dependency in CouchDB by this new spec
• remove the old and no longer maintained couchapp.spec and its dependency py2-restkit.spec

[muhammadimranfarooqi]

+1 to 735b9cd on slc7_amd64_gcc630.
Build log can be found here.

[amaltaro]

merge