[enh] #182: Add pyproject.toml and poetry.lock for Poetry usage

pyproject.toml

+[tool.poetry]
+name = "silkaj"
+version = "0.7.1"
+description = "Powerfull, lightweight, and multi-platform command line client written with Python for Duniter’s currencies: Ğ1 and Ğ1-Test."
+authors = ["Moul <moul@moul.re>"]
+maintainers = ["Moul <moul@moul.re>"]
+readme = "README.md"
+license = "AGPL-3.0-or-later"
+homepage =  "https://silkaj.duniter.org"
+repository = "https://git.duniter.org/clients/python/silkaj"
+documentation = "https://git.duniter.org/clients/python/silkaj/tree/dev/doc"
+keywords = ["g1", "duniter", "cryptocurrency", "librecurrency", "RTM"]
+
+[tool.poetry.dependencies]
+python = "^3.5.3"
+duniterpy = "^0.54.3"
+click = "^7.0"
+ipaddress = "^1.0"
+tabulate = "^0.8.3"
+texttable = "^1.6"
+PyNaCl = "^1.3"
+
+[tool.poetry.dev-dependencies]
+pre-commit = "^1.18"
+pytest = "^5.1"
+pytest-cov = "^2.7"
+pytest-asyncio = "^0.10.0"
+
+[build-system]
+requires = ["poetry>=0.12"]
+build-backend = "poetry.masonry.api"
+
+classifiers = [
+    "Development Status :: 5 - Production/Stable",
+    "License :: OSI Approved :: GNU Affero General Public License v3",
+    "Operating System :: OS Independent",
+    "Environment :: Console",
+    "Intended Audience :: End Users/Desktop",
+    "Intended Audience :: Developers",
+    "Natural Language :: English"
+]