Add Apache License V2 (#98)

* Add Apache License V2, PR template, contributing guidelines

---------

Co-authored-by: Madhavan Sridharan <[email protected]>

Author: msmygit

.github/pull_request_template.md

@@ -0,0 +1,11 @@
+<!--  Thanks for sending a pull request!  -->
+
+**What this PR does**:
+
+**Which issue(s) this PR fixes**:
+Fixes #<issue number>
+
+**Checklist:**
+- [ ] Automated Tests added/updated
+- [ ] Documentation added/updated
+- [ ] CLA Signed:  [DataStax CLA](https://cla.datastax.com/)

CONTRIBUTING.md

@@ -32,6 +32,26 @@ get started are described here.
   address a non-trivial issue that has been reported, you can follow the steps that the original user
   reported. Updating issues with such findings is immensely helpful to the maintainers.
 
+### Commits
+
+Keep your changes **focused**. Each commit should have a single, clear purpose expressed in its 
+message.
+
+Resist the urge to "fix" cosmetic issues (add/remove blank lines, move methods, etc.) in existing
+code. This adds cognitive load for reviewers, who have to figure out which changes are relevant to
+the actual issue. If you see legitimate issues, like typos, address them in a separate commit (it's
+fine to group multiple typo fixes in a single commit).
+
+Commit message subjects start with a capital letter, use the imperative form and do **not** end
+with a period.
+
+Avoid catch-all messages like "Minor cleanup", "Various fixes", etc. They don't provide any useful
+information to reviewers, and might be a sign that your commit contains unrelated changes.
+
+We don't enforce a particular subject line length limit, but try to keep it short.
+
+You can add more details after the subject line, separated by a blank line.
+
 ### Pull Requests
 
 All contributions to this project are made in the form of pull requests, including:
@@ -55,6 +75,9 @@ All contributions to this project are made in the form of pull requests, includi
   and requires some study of the codebase. If you take the time to understand the code a bit before submitting
   pull requests, then the maintainers will take the time to help you make your pull requests better.
 
+- Like commits, pull requests should be focused on a single, clearly stated goal.
+  Contributors need to sign the [DataStax CLA](https://cla.datastax.com/).
+
 ### Maintainers
 
 We are looking for more community ownership in this project. That means that we will be supportive of
@@ -133,4 +156,4 @@ For recognizing contributions, please follow [this documentation](https://allcon
 
 <!-- ALL-CONTRIBUTORS-LIST:END -->
 
----
+---

README.md

@@ -1,3 +1,4 @@
+[![License Apache2](https://img.shields.io/hexpm/l/plug.svg)](http://www.apache.org/licenses/LICENSE-2.0)
 [![Star on Github](https://img.shields.io/github/stars/datastax/cassandra-data-migrator.svg?style=social)](https://github.com/datastax/cassandra-data-migrator/stargazers)
 
 # cassandra-data-migrator
@@ -114,4 +115,4 @@ This mode is specifically useful to processes a subset of partition-ranges that
 # Contributors
 Checkout all our wonderful contributors [here](./CONTRIBUTING.md#contributors).
 
----
+---