Needed libyara-dev dependency not documented

[mosherbrian]

On Ubuntu 18.04 the installation instructions are incomplete. The libyara-dev package is required to build, otherwise the build fails with this message:

~/dexcalibur$ npm install

> yara@2.2.0 install /home/bmosher/dexcalibur/node_modules/yara
> node-gyp rebuild

make: Entering directory '/home/bmosher/dexcalibur/node_modules/yara/build'
  CXX(target) Release/obj.target/yara/src/yara.o
In file included from ../src/yara.cc:13:0:
../src/yara.h:8:10: fatal error: yara.h: No such file or directory
 #include <yara.h>
          ^~~~~~~~
compilation terminated.
yara.target.mk:105: recipe for target 'Release/obj.target/yara/src/yara.o' failed
make: *** [Release/obj.target/yara/src/yara.o] Error 1
make: Leaving directory '/home/bmosher/dexcalibur/node_modules/yara/build'
gyp ERR! build error
gyp ERR! stack Error: `make` failed with exit code: 2
gyp ERR! stack     at ChildProcess.onExit (/home/bmosher/.nvm/versions/node/v13.1.0/lib/node_modules/npm/node_modules/node-gyp/lib/build.js:194:23)
gyp ERR! stack     at ChildProcess.emit (events.js:210:5)
gyp ERR! stack     at Process.ChildProcess._handle.onexit (internal/child_process.js:272:12)
gyp ERR! System Linux 4.4.0-18362-Microsoft
gyp ERR! command "/home/bmosher/.nvm/versions/node/v13.1.0/bin/node" "/home/bmosher/.nvm/versions/node/v13.1.0/lib/node_modules/npm/node_modules/node-gyp/bin/node-gyp.js" "rebuild"
gyp ERR! cwd /home/bmosher/dexcalibur/node_modules/yara
gyp ERR! node -v v13.1.0
gyp ERR! node-gyp -v v5.0.5
gyp ERR! not ok
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! yara@2.2.0 install: `node-gyp rebuild`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the yara@2.2.0 install script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR!     /home/bmosher/.npm/_logs/2019-11-20T04_18_33_659Z-debug.log

Fixing this requires you install the missing package:

sudo apt-get install libyara-dev

[FrenchYeti]

Thanks ! I introduced yara dependency into package.json production file by error. I remove it, i will propose a way to install it optionnaly later with yara feature. Sorry for time waste and thank you for issue :)