Update composer.json

Allow use of Symfony Event Dispatche releases later than 2.1, i.e., the current dev version.  (This is necessary for Drupal, which is tracking Symfony master.)
Fix composer syntax.
Merge pull request #187 from Crell/patch-1

Update composer.json
Syncing deps with guzzle/guzzle
Adding setErrorResponses() to Operation
Make 3.0.x-dev installable. (3.0.*@dev)
Fixed the dataProvider in the CurlHandleTest.

- dataProvider methods can't mark a test as incomplete, only the
  test method itself can, so I removed .
- Made dataProvider use 'phpunit.xml.dist' over 'phpunit.xml' for
  the test to pass without phing build.
- Fixed corresponding test case to not check for 'application/xml'
  and 'phpunit.xml' but rather 'application/octet-stream' and
  'phpunit.xml.dist'
Optimizing CurlMulti implementation to better deal with exponential backoff and -1 return values from curl_multi_select
Merge remote-tracking branch 'simensen/make-3-0-x-dev-installable'
Merge remote-tracking branch 'tploch/fix-curl-handle-test'
Tagging 3.0.6
Allowing a filename to be passed into $request->setResponseBody()
Adding a response_body location to service descriptions to more easily change the location in which a response entity body is saved
Cleaning up the Collection object inject method and adding missing test
Fixing phar detection when forcing a cacert to system if null or true
Tagging for 3.0.7
Removing hard dep on BackoffPlugin
Making blocking a curl multi loop more generic so it can be used in other places
Closes #196
Cleaning up CurlException messages and adding a getCurlInfo() method
Making it easier to work with exceptions thrown during multi transfers. Addresses #197
Easier exception thrown when sending commands in parallel
Adding CommandTransferException
Cleaning up Exceptions thrown from multi transfer
Closes #197