Issue #1: Add core tables schema

Signed-off-by: Lucas Fernandes de Oliveira <lfoliveira@inf.ufpr.br>

workspace/create/00-core-tables.sql

+CREATE TABLE form (
+    id SERIAL PRIMARY KEY,
+    latest_version INTEGER
+);
+
+CREATE TABLE form_version (
+    id SERIAL PRIMARY KEY,
+    id_form INTEGER,
+    version INTEGER,
+    title TEXT,
+    description TEXT
+);
+
+CREATE TABLE input (
+    id SERIAL PRIMARY KEY,
+    id_form_version INTEGER,
+    placement INTEGER,
+    input_type TEXT,
+    question TEXT,
+    description TEXT
+);
+
+CREATE TABLE input_validation (
+    id SERIAL PRIMARY KEY,
+    id_input INTEGER,
+    validation_type TEXT,
+    argument_number INTEGER
+);
+
+CREATE TABLE input_validation_argument (
+    id SERIAL PRIMARY KEY,
+    id_input_validation INTEGER,
+    placement INTEGER,
+    argument TEXT,
+);
+
+CREATE TABLE form_version_answer (
+    id SERIAL PRIMARY KEY,
+    id_form_version INTEGER,
+    timestamp TIMESTAMP
+);
+
+CREATE TABLE input_answer (
+    id SERIAL PRIMARY KEY,
+    id_form_version_answer INTEGER,
+    id_input INTEGER,
+    value TEXT,
+    placement TEXT
+);