Skip cert verification for test

cc @jch as I'm unsure if we want to go this route or make the cert verifiable instead
Cache cacert.pem for local testing, wire up override, VM-aware path
Fix build badge URL

Was pointing at the github/ruby-net-ldap fork.
Merge branch 'master' into starttls-test-verify-none
Add verify none test, differentiate
Merge pull request #166 from ruby-ldap/starttls-test-verify-none

Specify certfile to verify SSL certs against in tests
Bump version to 0.10.0
Add changelog to history file
Fix minor release notes in README
Merge pull request #171 from ruby-ldap/release-0.10.0

Release 0.10.0
Release 0.10.0
test ber encoding of message_id > 128
Fix BER encoding test fixture for int value 128
Try padding based on most significant bit
Pad based on most significant bit in octet

Was just looking at most significant bit.
Fix the expected encoded value for 255
Add negative reference encoded values, but disable
Fix expected encoded integers

Makes the format consistent (hex), and updated based on various sample sources.
Add roundtrip encoding/decoding tests for samples
Fix negative Fixnum encoding