Always have bash_readline setup bash with readline

If no readline dir is specified, have bash look in the default
locations rather than using builtin readline.

Updated zsh to 5.7

Use correct flag for setting up bash in readline tests

Updated README

Merge pull request #51 from ardagnir/1.0

1.0

Merge pull request #48 from ardagnir/0.9

0.9

Merge pull request #45 from ardagnir/0.8.4

Only run read test for bash/readline

Merge pull request #44 from ardagnir/0.8.3

0.8.3

Merge pull request #43 from ardagnir/0.8.2

Updated readline to 7.0

Merge pull request #42 from ardagnir/0.8.1

0.8.1