Styleguide fixes
removed PR from the bug list
Removed the unused $force paramter in Email::_smtp_connect()
removed a stray tab
Merge pull request #2256 from nisheeth-barthwal/develop

Added keep-alive connection to SMTP. Fixed socket read/write timeouts. Added PHP useragent.
Set the --dev option for travis composer install command.
Set the --no-progress option for travis composer install command
Attempt to get travis to work by adding php-invoker
Revert "Attempt to get travis to work by adding php-invoker"

This reverts commit 1396a958a5b96cc6c617ae725034fa58542acd25.
Simplify the composer command
See how many errors are produced when no dependencies are included
vfsStream is required for travis
Merge branch 'develop' of github.com:EllisLab/CodeIgniter into develop
Revert all changes to see if travis just doesn't like me.
Fix a code comment in Upload->_file_mime_type()

Availability of dangerous functions is now tested using function_usable().
Fix typos in upgrade_300.rst
Add an upgrade note about change in the results of Directory Helper's directory_map()

see issue #1978
Merge pull request #2260 from vlakoff/develop-2

Add an upgrade note about change in the results of Directory Helper's directory_map()
Merge pull request #2258 from vlakoff/develop

Fix a code comment in Upload->_file_mime_type()
Fix form_upload() test