Added README and LICENSE

LICENSE

+MIT License
+
+Copyright (c) 2018 Vadym Gidulian
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

+# Mailer
+Mailer service for sending templated emails.
+
+## Usage
+
+1. Pull Docker image:
+    ```bash
+    docker pull registry.git.gvia.group/microservices/mailer
+    ```
+
+2. Run container:
+    ```bash
+    docker run \
+        -v $PWD/templates:/app/templates:ro \
+        -e SMTP_HOST=example.com \
+        -e SMTP_PORT=465 \
+        -e SMTP_SECURE=true \
+        -e SMTP_USER=mail@example.com \
+        -e SMTP_PASSWORD=password \
+        registry.git.gvia.group/microservices/mailer
+    ```
+    or use Docker Compose:
+    ```yaml
+    version: '3'
+    
+    services:
+      mailer:
+        image: registry.git.gvia.group/microservices/mailer
+        environment:
+          SMTP_HOST: example.com
+          SMTP_PORT: 465
+          SMTP_SECURE: true
+          SMTP_USER: mail@example.com
+          SMTP_PASSWORD: password
+        volumes:
+          - ./templates:/app/templates:ro
+    ```
+
+### Environment variables
+
+- `CORS_ALLOW_ORIGIN`: Value of `Access-Control-Allow-Origin` header. Default: `*`
+- `SMTP_HOST`: SMTP server's host
+- `SMTP_PORT`: SMTP server's port
+- `SMTP_SECURE`: If truthy the connection will use TLS when connecting to server.
+  If falsy (the default) then TLS is used if server supports the STARTTLS extension.
+  In most cases set this value to true if you are connecting to port 465. For port 587 or 25 keep it false
+- `SMTP_USER`: Username
+- `SMTP_PASSWORD`: Password
+- `SMTP_SENDER`: Sender's email address. Default: `SMTP_USER`
+
+### Templates
+
+Templates are located in `/app/templates` directory. Supported template engines are:
+- [EJS](https://github.com/mde/ejs) (`.ejs` files)
+- [Handlebars](https://github.com/wycats/handlebars.js) (`.hbs` or `.handlebars` files)
+- [Pug](https://github.com/pugjs/pug) (`.pug` files)
+- Plain text (all other files with or without extension)
+
+In template engines which support includes root for absolute paths is set to `/app/templates`.
+I.e. `/includes/header` will be resolved as `/app/templates/includes/header`.
+
+### API
+
+[Swagger](https://generator.swagger.io?url=https%3A%2F%2Fgit.gvia.group%2Fmicroservices%2Fmailer%2Fblob%2Fmaster%2Fopenapi.yaml)