Add a separate template for bug reports

Using Github's new feature to have separate templates for
bug reports and feature requests.

Author: leouieda

.github/ISSUE_TEMPLATE/bug_report.md

@@ -0,0 +1,37 @@
+---
+name: Bug report
+about: Create a report to help us improve
+
+---
+
+**Description of the problem**
+
+<!-- Please be as detailed as you can when describing an issue. The more information we have, the easier it will be for us to track this down. -->
+
+**Full code that generated the error**
+
+```python
+PASTE CODE HERE
+```
+
+**Full error message**
+
+```
+PASTE ERROR MESSAGE HERE
+```
+
+**System information**
+
+* Operating system:
+* Python installation (Anaconda, system, ETS):
+* Version of GMT:
+* Version of Python:
+* Version of this package:
+* If using conda, paste the output of `conda list` below:
+
+<details>
+<summary>output of conda list</summary>
+<pre>
+PASTE OUTPUT OF CONDA LIST HERE
+</pre>
+</details>