Specify tighter version on pdfjs-dist in package.json

[mattddean]

Thought the package-lock.json file contains the correct version, the version pattern for pdfjs-dist allows for a version of pdfjs-dist that seems to rename the es5 directory to legacy. Thus, an error is thrown when this package is used as a dependency of another project without that dependent project explicitly setting its pdfjs-dist version to 2.7.570

Please update:

"pdfjs-dist": "^2.7.570"

to

"pdfjs-dist": "~2.7.570"

[k-yle]

thanks for the report, I've fixed this in #58. As of v1.1.1 we pin dependencies to prevent this from happening again