[FIXED JENKINS-15940] WARNING: Caught exception evaluating: descriptor.getHelpFile(attrs.field). Reason: java.lang.NullPointerException

Require UPLOAD_PLUGINS permission for install-plugin cli command
Thanks !

minor textual improvements on Manage Jenkins page to improve appearance
Thanks

Added a trailing period to english AboutJenkins.Description because it
was the only message on that page having none.

this changes the rendering from
  ...functionality of Jenkins.(updates available)
to 
  ...functionality of Jenkins. (updates available)
which looks nicer.

Had to use  , regular whitespace wouldn't do.

German translations for AboutJenkins and OldDataMonitor links
Thanks

Otherwise it's not very obvious how the job name is in the abc/def/ghi notation
that's used in CLI and such.

[FIXED JENKINS-15839] wrong unicode characters on german Manage Jenkins page

page

the german translations used the character codes CEDILLA (00B8) and PER
MILLE SIGN (2030) instead of LATIN SMALL LETTER U WITH DIAERESIS (00FC)
and LATIN SMALL LETTER A WITH DIAERESIS (00E4)

These versions have a better API that supports Channels in general, not
just SlaveComputer.

[FIXED JENKINS-15836] Slave's Name should be trimmed of spaces at the beginning and end of the Name on Save

Fix X-Text-Size header description

Otherwise get a useless “null is missing its descriptor” from Jenkins.getDescriptorOrDie.

X-Text-Size actually contains the offset to be used for the next start parameter, this header does contain the chunk size itself, and hence the client only needs to pass X-Text-Size header value as the next start.

The value of X-Text-Size header is the return value of writeLogTo method, which is the chunk size + the previous start. https://github.com/jenkinsci/jenkins/blob/master/core/src/main/java/hudson/model/LargeText.java#L171

pages.