Correct the Manifest.ini path and moveback the signatures.db to mythril root

MANIFEST.in

@@ -1,2 +1,2 @@
-include mythril/disassembler/signatures.db
+include signatures.db
 include mythril/analysis/templates/*

mythril/mythril.py

@@ -126,7 +126,7 @@ class Mythril(object):
         if not os.path.exists(db_path):
             # if the default mythril dir doesn't contain a signature DB
             # initialize it with the default one from the project root
-            parent_dir = Path(__file__).parent
+            parent_dir = Path(__file__).parent.parent
             copyfile(str(parent_dir / "signatures.db"), db_path)
 
         return mythril_dir

setup.py

@@ -102,7 +102,7 @@ setup(
     tests_require=["pytest>=3.6.0", "pytest_mock", "pytest-cov"],
     python_requires=">=3.5",
     extras_require={},
-    package_data={"mythril.analysis.templates": ["*"], "mythril": ["signatures.db"]},
+    package_data={"mythril.analysis.templates": ["*"], "": ["signatures.db"]},
     include_package_data=True,
     entry_points={"console_scripts": ["myth=mythril.interfaces.cli:main"]},
     cmdclass={"verify": VerifyVersionCommand},