0.91.0

Changes:

• Bug fix for multiple single quotes in cmd string not being handled correctly - #39
• run_command now correctly uses the login user's defined shell. Previously bash was always used.
• run_command has gained a new parameter, use_shell. When set to False, command is run without a shell. Defaults to True which is existing behaviour. Useful for cases where, for example, commands run by the library are exposed to user input and could lead to shell injection vulnerabilities.
• run_command has gained shell parameter to allow overriding of the shell to use. For example, run_command(<..>, shell='zsh -c') or run_command(<..>, shell='bash -c').