--skip-requirements flag should be binary and not require any inputs

[craig8]

Describe the bug
Currently a value must be passed to --skip-requirements of the vctl install command, but I don't believe it is necessary. This command will skip any requirements.txt file that is located in the root of the agent directory.

To Reproduce
Steps to reproduce the behavior:

(volttron) craig8@WE48687:~/repos/volttron$ vctl install services/core/PlatformDriverAgent/ --skip-requirements
usage: vctl command [OPTIONS] ... install [-h] [-c FILE] [--debug] [-t SECS] [--msgdebug MSGDEBUG] [--vip-address ZMQADDR] [--skip-requirements SKIP_REQUIREMENTS] [--tag TAG]
                                          [--vip-identity VIP_IDENTITY] [--agent-config AGENT_CONFIG] [-f] [--priority PRIORITY] [--start] [--enable] [--csv] [--json]
                                          [-st AGENT_START_TIME]
                                          install_path
vctl command [OPTIONS] ... install: error: argument --skip-requirements: expected one argument
(volttron) craig8@WE48687:~/repos/volttron$ vctl install services/core/PlatformDriverAgent/ --skip-requirements 1
Agent 4df35ad5-2403-4fd8-89be-281a5c95c10a installed