Release 2.5.2

Updated dependencies to support go1.16.

Release 2.5.1

Fix for the build on homebrew.

Release charmstore-client 2.5.0

Update charmstore-client with newer versions of dependencies.

Release charmstore-client 2.2.0

New & noteable in this release:

Add term publishing plugin commands to whitelist.
Add support for new charm store channels: stable, candidate, beta and edge.
The development channel has been replaced with edge.
Rename publish subcommand. It is now called "charm release" to be more in line
with snappy semantics.

Other improvements:

Add bash completion.
Generate man pages.
Cache plugin help.
Use a whitelist and call charm-tools-commands to extend the whitelist.
Change push resource to attach, --resource option.

2.1.1: Merge pull request #47 from frankban/update-dependencies-1460554190

Update dependencies: include new idm client.