use consistent variables across all jenkins jobs for streams, TP versions, etc.

We have a number of inconsistencies between jobs / pom.xml:

• JBTCENTRALTARGET_VERSION -> TARGET_PLATFORM_CENTRAL_MAX
• TARGET_PLATFORM_VERSION vs. TARGET_PLATFORM_VERSION_MIN
• TARGET_PLATFORM_VERSION_MAXIMUM vs. TARGET_PLATFORM_VERSION_MAX
• jbosstools_site_stream -> stream_jbt
• JBT_buildversion -> version_jbt, versionWithRespin_jbt
• JBDS_buildversion -> version_ds, versionWithResin_ds
• JBDSVersion -> devstudioReleaseVersion

Should standardize these.

Can also (where applicable) script the relationship between version_* and versionWithRespin_*:

version_jbt=$(echo ${versionWithRespin_jbt} | sed -e '/[abcdwxyz]$/ s/\(^.*\)\(.$\)/\1/')
version_ds=$(echo ${versionWithRespin_ds} | sed -e '/[abcdwxyz]$/ s/\(^.*\)\(.$\)/\1/')