Add version-dependent display filter flag
Address review comments
Merge pull request #39 from bbayles/display-filter

Add version-dependent display filter flag
Implimented decryption. Dirty, but it works
refactored to make decryption easier to impliment in other kinds of captures (not just FileCaps)
Implimented decryption in LiveCap and RemoteCap
encryption_type is now case insensitive.
Updated documentation with information about decryption.

Also noted remote captures in README.md
Final update to documentation.
removed commented import statement from a previous iteration.
UnknownEncyptionStandardException now gives you more feedback.
Added gvar SUPPORTED_ENCRYPTION_STANDARDS to pyshark.Capture that contains all the supported encryptions.
Updated docs with SUPPORTED_ENCRYPTION_STANDARDS
Removed unneccesary string escapes.
Merge pull request #42 from mcarlsonallion/master

Enabled 802.11 Decryption
Merge branch 'master' into async-read

Conflicts:
	src/pyshark/__init__.py
	src/pyshark/capture/capture.py
	src/pyshark/capture/file_capture.py
	src/pyshark/capture/live_capture.py
Reapplied @mcarlsonallion changes

decryption support