Add copyright headers to all files

[cecilia-donnelly]

We need to add this header to all files:

Copyright (c) <year(s) modified> <copyright holder>

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.

[kfogel]

A copyright notice header is more than that actually. Will explain in person, but see http://opensource.org/faq#apply-license as a starting point, and see redcross/smoke-alarm-portal@f525656 as an example of a commit that adds copyright notices.