Resolve several travis-ci issues

Resolve several travis-ci issues

MBEDTLS_VERSION, OPENSSL_VERSION were defined twice - in both
.travis.yml  and .travis/build-deps.sh files, the last one
defined OPENSSL_VERSION via nonexistent OPENSSL_VERION
variable, which lead us to use openssl-1.0.1 instead of
openssl-1.0.2, I removed variable definition from build-deps.sh

"cache: [ apt: true ]" is not a travis supported option, it was
introduced by mistake, I removed it

LD_LIBRARY_PATH was defined for the entire test run, it includes
custom openssl build, which was picked by "wget", so "wget"
could not verify SSL cert at https://www.openssl.org sometimes.
We do not want wget to pick our custom LD_LIBRARY_PATH, so I moved
that variable to "script" section

LD_LIBRARY_PATH was defined for both linux and osx environments,
for the second DYLD_LIBRARY_PATH must be defined instead

v2: Upgrade openssl, mbedtls to the most recent versions
v3: DYLD_LIBRARY_PATH was defined via LD_LIBRARY_PATH by mistake

Acked-by: Selva Nair <selva.nair@gmail.com>
Message-Id: <1485673091-7600-1-git-send-email-chipitsine@gmail.com>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg13983.html
Signed-off-by: David Sommerseth <davids@openvpn.net>