Adds autodetection of ContentType for AwsS3 adapter.
Makes content-type detection configurable when adapter is instantiated.
Adds description to composer.json about how the suggested ext-fileinfo extension is used.
Defaults content-type detection to false in AwsS3 adapter to prevent breaking existing usage.
Merge pull request #236 from woodsae/awss3-automatic-content-type-detection

AwsS3 Automatic Content-Type Detection
SizeCalculation from FileSystem

Using the FilesSystem for calculating the size instead of reading the content. This can save a lot of memory using the Local adapter that implements the new SizeCalculator interface.
Fixed spec tests for new size calulation
Don't override environment's umask.
Merge pull request #238 from robocoder/patch-1

Don't override environment's umask.
Merge pull request #237 from eluceo/master

SizeCalculation from FileSystem
fixed leak of resource in sftp->ensureDirectoryExists()

cleanup after a successfull call to opendir(), so the OS will not get
out of resource handles on long running processes.
Merge pull request #242 from staabm/sftpleak2

fixed leak of resource in sftp->ensureDirectoryExists()