Handle invalid security scheme components

[kylef]

The parser is currently crashing for certain inputs, for example:

openapi: 3.0.0
info:
  title: abc
  version: xyz
paths: {}
components:
  securitySchemes:
    Foo: {}

TypeError: Cannot read property 'meta' of undefined
    at object.forEach (/Users/kyle/Projects/apiaryio/api-elements.js/packages/fury-adapter-oas3-parser/lib/parser/oas/parseComponentsObject.js:154:17)
    at content.forEach.item (/Users/kyle/Projects/apiaryio/api-elements.js/node_modules/minim/lib/primitives/ObjectElement.js:203:63)
    at Array.forEach (<anonymous>)
    at ObjectElement.forEach (/Users/kyle/Projects/apiaryio/api-elements.js/node_modules/minim/lib/primitives/ObjectElement.js:203:25)
    at pipeParseResult (/Users/kyle/Projects/apiaryio/api-elements.js/packages/fury-adapter-oas3-parser/lib/parser/oas/parseComponentsObject.js:152:14)
    at run (/Users/kyle/Projects/apiaryio/api-elements.js/packages/fury-adapter-oas3-parser/lib/pipeParseResult.js:60:25)
    at XWrap.f (/Users/kyle/Projects/apiaryio/api-elements.js/node_modules/ramda/src/reduceWhile.js:40:27)
    at XWrap.@@transducer/step (/Users/kyle/Projects/apiaryio/api-elements.js/node_modules/ramda/src/internal/_xwrap.js:12:17)
    at _arrayReduce (/Users/kyle/Projects/apiaryio/api-elements.js/node_modules/ramda/src/internal/_reduce.js:11:34)
    at _reduce (/Users/kyle/Projects/apiaryio/api-elements.js/node_modules/ramda/src/internal/_reduce.js:45:12)