Added .gitignore file

Also removed a Vim Swp file.
Reorganization of the repository, tools added.

The main topics were moved to their respective folder, and contributing
information to its own. A new tools repository was created which will
house all the software used in CTFs and can be referenced from the topic
explanations.
Minor touch ups to READMEs

Proof-read all the READMEs.

Added blockquotes to starting of some.

Made a few url changes too.
Added Hex Editor and Terminal to tools.
tools README redone
clean up of existing write-ups, modified contribuion standard
typo in steg
new steg
typo
Add link to “Reverse engineering for beginners”
Added some to web and reversing
Topics README.md
Added file write-up
Rewrote intro, crypto
redo some of the crypto sections
More cryptography sections redone
start to web and changed steg
extended web section
reorganization
fixes in numbering