add release and dev requirements for enaml
Merge branch 'master' into use-multiple-runs-for-enaml

# Via Ioannis Tziakos (2) and IoannisTziakos (1)
* master:
  move cython installation out of the dev_requirements
  move pip install inside the intall section
  move cython to the requirements file
  add a verbose option to see what went wrong
  add a verbose option to see what went wrong

Conflicts:
	.travis.yml
fix typo
release should take place on the latest availabel stable versions
rename env variable
add enable on the external packages list
enother rty at persuading pip to install enable
move the allow-ecternal options to the requirements files
fix typo
one more time
more typos
Merge pull request #46 from enthought/use-multiple-runs-for-enaml

add release and dev requirements for enaml