Bosh trap refactor/security fix

[Houlistonm]

Current implementation of multiple traps

trap 'rm -f ${ssh_key_path}' EXIT`
trap 'rm -f ${bosh_ca_path}' EXIT`

has the effect of the second trap replacing the first and allowing files to accumulate in /tmp.

Refactored so a single trap will remove both files on exit.

[edwardecook]

Same as #10 looks good but need to enable Pivotal CLA bot.

[pivotal-issuemaster]

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[Houlistonm]

Thank you.

…

On Thu, Aug 29, 2019 at 8:14 AM Ed Cook ***@***.***> wrote: Merged #11 <#11> into master. — You are receiving this because you modified the open/close state. Reply to this email directly, view it on GitHub <#11?email_source=notifications&email_token=AFZN4T4ZL3CYOKCJIH3ZPA3QG64TFA5CNFSM4IQGTVP2YY3PNVWWK3TUL52HS4DFWZEXG43VMVCXMZLOORHG65DJMZUWGYLUNFXW5KTDN5WW2ZLOORPWSZGOTKMZ35A#event-2593758708>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AFZN4T5REYJSUOLQP5VSVLLQG64TFANCNFSM4IQGTVPQ> .