Add an optional mode for mkdir

This is a back-compatible change, to be able to choose a mode for mkdir.
Close underlying connection on destruction
Cleans up use statements and docblocks for File class.
Merge pull request #245 from woodsae/file-class-cleanup

Cleans up use statements and doc blocks for File class
Merge pull request #244 from staabm/patch-1

Close underlying connection on destruction
Merge pull request #240 from garak/patch-1

Add an optional mode for mkdir
Fixed file size calculation for Filesystems that do not implement SizeCalculator
Update S3 docs. Using AwsS3 and S3Client with new AWS SDK.
Merge pull request #247 from eluceo/master

FIX file size calculation for Filesystems that dont implement SizeCalculator
Merge pull request #251 from undernewmanagement/patch-1

Update S3 docs. Using AwsS3 and S3Client with new AWS SDK.
Fix stream_wrapper_unregister error issue

This should fix issue #256
Fix readme typo
Merge pull request #258 from allanbrault/patch-1

Fix readme typo
AwsS3 adapter: fixed rename
Merge pull request #260 from teohhanhui/patch-s3-rename

AwsS3 adapter: fixed rename
Creating new directories did not work.

When using write() or rename() no new directories have been created, if __construct(..., ..., false) was given.

Seemed to be typo, because all calls to ensureDirectoryExists give a value for $create. Because of this, the default value was removed.
Throw expected exception even-though a custom error handler is specified
Remove use statement for "PhpSpec\Exception\Exception"
Restore error handler after test steps are finished
Merge pull request #261 from h4cc/master

PhpseclibSftp: Creating new directories did not fully work.