Create sfNoMailer.class.php with the same signature as sfMailer

This allow to avoid SwiftMailer initialization on all requests even if the application does not send any email.
Add NoMailer to the Changelog
Add a performance section with the no mailer part
Typo
Merge pull request #18 from laurentb/fixpkg

Fix PEAR packaging
Merge pull request #17 from damienalexandre/sfnomailer

Allow to disable SwiftMailer for real by using sfNoMailer
Do no remove .* files when clearing the cache

Thanks @nexik for the idea
Merge pull request #20 from j0k3r/dont-remove-dot-files

Do no remove .* files when clearing the cache
Fix unit tests
Fix travis configuration
Alias branch master branch to version 1.5 for tagging

Close #24
Merge pull request #21 from LExpress/fix-array-widget

[widget] Fix array to string convertion when using renderId with an array as value
Prepare release 1.5
Bump version to 1.5.1
Update install note
project:optimize Continue in case of execption when loading a module config
Merge pull request #27 from LExpress/project-optimize

project:optimize Continue in case of exception when loading a module config
Add a warning in README about not using this fork for new projects
Merge pull request #28 from damienalexandre/warningReadMe

Add a warning in README about not using this fork for new projects
Restore sfPropelPlugin