Add support for IAM roles and temp tokens

Including:
Refresh temp tokens on every request.
Add support for roles in S3, CloudFront and SimpleDB.
Add support for AWS_CREDENTIALS_FILE env variable and the file it references
Merge pull request #127 from dudyk/IAM

Add support for IAM roles and temp tokens
Version 1.5.0-alpha2
Updated s3cmd.1 manpage for v1.5.0-alpha2

One commit too late, never mind...
fix single file sync local2remote traceback, bug #128

Fixes https://github.com/s3tools/s3cmd/issues/128

In the single file transfer case, the remote_list was getting created
as a dict, rather than as a SortedDict as it should be.
sync remote2remote: set target_uri on updated files too, bug 131

fixes bug https://github.com/s3tools/s3cmd/issues/131

We were not setting the target_uri field on files that had changed,
only on files that were to be newly uploaded.  This was causing a
traceback when referencing the target_uri field when copying the
changed file.
Merge pull request #129 from mdomsch/bug/128

fix single file sync local2remote traceback, bug #128
Merge pull request #133 from mdomsch/bug/131

sync remote2remote: set target_uri on updated files too, bug 131
Split md5/hardlink stuff out of SortedDict into FileDict

I should not have overloaded SortedDict with all the md5 and hardlink
tracking stuff which only used by file lists.  There are other uses of
SortedDict elsewhere in the app that need not be cluttered by these
additional features in SortedDict.

Solution: derive new class FileDict from SortedDict, and put the md5
and hardlink tracking code into that.  Then use FileDict instead of
SortedDict where those features are needed.
Add quiet option to silence output on stdout
Replaced mktemp with alternative temp file generation based on secure randoms in order to avoid owner-restricted permission issues with mktemp files
Added cleanup of temp file if error or keyboard interrupt occurs during transfer.
cleanup
Revert "cleanup"

This reverts commit 701a66413d47fc34aec9269dbf0bb19fb28e4359.
Revert "Replaced mktemp with alternative temp file generation based on secure randoms in order to avoid owner-restricted permission issues with mktemp files"

This reverts commit 640a88575a3f637ecdf6b6f677913020129aca04.
Set permission on copied file based on umask.
Updated references to temp file in exception handlers
Merge pull request #136 from tjasond/master

mktemp permission issue, fix
Wrap quiet option in try/except
Merge pull request #135 from sidprak/add-quiet-option

Add --quiet option to silence output on stdout