fix(agent): correctly handle false observe values

[JKRhb]

This is a fix for coapjs/coap-cli#136. The case where the observe parameter is set to false has not been handled correctly, yet, causing clients to hang after a request has been finished.

[coveralls]

Pull Request Test Coverage Report for Build 2348435791

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

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Details

• 1 of 1 (100.0%) changed or added relevant line in 1 file are covered.
• 2 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.4%) to 91.35%

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Files with Coverage Reduction	New Missed Lines	%
lib/server.ts	2	86.94%

Totals
Change from base Build 2343713153:	-0.4%
Covered Lines:	2840
Relevant Lines:	3053

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💛 - Coveralls