Make install command
Add CONTRIBUTING based on #15

https://github.com/ginatrapani/todo.txt-cli/issues/15
Also include title
ensure GREP_OPTIONS doesn't break listproj output
Merge pull request #99 from benjaminoakes/master

Add CONTRIBUTING for GitHub integration
Added test case for GREP_OPTIONS
Merge pull request #90 from danohuiginn/master

Make install
Merge pull request #101 from Thann/grep_options_fix

ensure GREP_OPTIONS doesn't break listproj output
Install using 'install' instead of 'cp'. Install 'todo.sh' instead of 'todo'
Allow the use of global config file

If not found elsewhere, look for the config file in /etc/todo/config.
`make install` installs a global config file, setting TODO_DIR=~/.todo.
todo.sh creates TODO_DIR if it doesn't exist.
ENH: Allow configuring null data files and then don't create them.

Request from exatto (http://article.gmane.org/gmane.comp.diary.todotxt/4699), who doesn't want to use done.txt and report.txt.

Also consider character devices (-c; /dev/null is one) in the file existence checks so that no empty file is then created.
Simplify empty data file creation.

No need to use the external cp command; shell redirection will create an
empty file for us.
Fix changelog link in readme
Merge pull request #117 from pdclark/master

Fix changelog link in readme
Merge pull request #116 from inkarkat/enh-allow-null-files

Allow configuring null data files and then don't create them.
Add .travis.yml

`make dist && sudo make install` are used
to install to /usr/local. `make test` then
verifies the changes.
Add Build Status to README
Merge pull request #123 from joshmoore/24pr-travis-yml

Enable Travis-CI
Update build status
Merge pull request #111 from mgarrido/global_opts

Allow the use of a global config file