Automatically re-hash shell commands after installing new tool version

[nirvana-msu]

Steps to reproduce

1. Install some tool using some other way (not through asdf)
2. Run the tool. At this point bash will hash the full path to the executable (so that next time it will avoid searching $PATH)
3. Install another version of the tool using asdf
4. Set the version you want to use, e.g. asdf global <tool> x.y.z
5. Run the tool.

Expected behavior

I would expect asdf shim to take over and execute the global version I've configured.

Actual behavior

Bash just takes the hashed executable path of the original tool, bypassing our shim. You can confirm this by running:

$ type <tool>
<tool> is hashed (/snap/bin/<tool>)

Environment

OS: Linux / Windows

asdf version:

0.6.3

Most other version managers clear hashes after installing a new version of the tool, e.g. you can see pyenv does it here.

It's simply a matter of running hash -r (for bash, at least) after the installation is complete. This can easily puzzle users who are not familiar with executable path hashing in bash.

P.S. Here is a nice stackoverflow answer explaining path hashing in bash.

[jayvdb]

Similar to #409

[Stratus3D]

@nirvana-msu, is this similar enough to #409 that I can close this issue?