Favours OpenSSL environment variables: SSL_CERT_FILE and SSL_CERT_DIR

[meghfossa]

Overview

This PR modifies System.X509's getSystemCertificateStore method, to favour OpenSSL environment variables (as used by git, curl, etc) namely:

• SSL_CERT_FILE
• SSL_CERT_DIR

If SSL_CERT_FILE or SSL_CERT_DIR values do not exist, previously implemented certificationStore is yielded.

Order of precedence:

1) SSL_CERT_FILE (OpenSSL conventional env name) 2) SSL_CERT_DIR (OpenSSL conventional env name) 3) SYSTEM_CERTIFICATE_PATH (Unix Only - Existing implementation)

To-do

• [x] Regression Test on Linux
• [x] Regression Test on Windows
• [x] Regression Test on OSX

Reference

• 118

• Open SSL CTX Load

[meghfossa]

@vincenthz tagging your for review. PR is fairly small.