Added signer module.#4

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racerxdl wants to merge 3 commits intokiddouk:masterfrom

racerxdl:master

Commits on Jan 18, 2018

Added signer module. Still its faster calling gpg2 directly
racerxdl
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Commits on Jan 22, 2018

Fix missing uninstd include and readme
racerxdl
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Commits on Feb 9, 2018

Avoid buffer overflow in password callback
racerxdl
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