Add release note instructions
Describe new release note dev process

For upcoming contributions, every contributor should document the contributed
changes, before merging the PR.
Add release notes for upcoming versions
Remove contributors for current release notes
Rename Changes section to API changes
Add intro to release notes
Add release notes template
Merge pull request #1023 from ahojnnes/release

New release note process
Clarify release procedure doc
Merge pull request #1093 from tonysyu/clarify-release-procedure

Clarify release procedure doc
pil_plugin can import and export from memory

- added capability to import and export to PIL Image
  objects, not just files - allows for converting
  to and from PIL image objects without writing
  to disk
- no unit test yet
added tests for roundtrip export and import

- and corrected error in imexport - wasn't using imsave code
  correctly
- split imsave into imsave and imexport functions to reuse
  imsave code
added a space character to trigger travis build
fixed bad indent
improved name of pil import/export functions

- to make it clear what the functions actually do:
  ndarray_to_pil() and pil_to_ndarray()
- as per code review feedback
- updated tests to use the new function names

- incoming change to pil_plugin assumed PIL Image
  objects will always be from files; this is
  not always true anymore. Now pil_plugin
  checks to see if the Image came from a file
  before trying to close its associated file.