replace ssh2.cr (#374)

reasons for replacement
* project inactivity
* all IO blocks the crystal lang event loop
* incompatible with crystal 0.7+

README.md

@@ -116,7 +116,7 @@ Contributions are welcome. Please take a quick look at the [contribution guideli
  * [pledge.cr](https://github.com/chris-huxtable/pledge.cr) - Bindings for OpenBSD's `pledge(2)`
  * [posix](https://github.com/ysbaddaden/posix) - POSIX/C bindings
  * [soundfile](https://github.com/mjago/soundfile) - Bindings for [libsndfile](http://www.mega-nerd.com/libsndfile/) library
- * [ssh2.cr](https://github.com/datanoise/ssh2.cr) - Bindings for libssh2 library
+ * [ssh2.cr](https://github.com/spider-gazelle/ssh2.cr) - Bindings for libssh2 library
  * [syslog.cr](https://github.com/chris-huxtable/syslog.cr) - Bindings for `syslog`
  * [termbox-crystal](https://github.com/andrewsuzuki/termbox-crystal) - Bindings and extension library for [termbox](https://github.com/nsf/termbox) (terminal UI library)
  * [x11-cr](https://github.com/TamasSzekeres/x11-cr) - X11 bindings