Allow configured numbers for FollowMe to be greater than 90 characters

When parsing a 'number' defined in followme.conf, FollowMe previously parsed
the number in the configuration file into a buffer with a length of 90
characters.  This can artificially limit some parallel dial scenarios.  This
patch allows for numbers of any length to be defined in the configuration
file.

Note that Clod Patry originally wrote a patch to fix this problem and received
a Ship It! on the JIRA issue.  The patch originally expanded the buffer to 256
characters.  Instead, the patch being committed duplicates the string in the
config file on the stack before parsing it for consumption by the application.

(closes issue ASTERISK-16879)
Reported by: Clod Patry
Tested by: mjordan
patches:
  followme_no_limit.diff uploaded by Clod Patry (license #5138)

Slightly modified for this commit.
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Merged revisions 372390 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 372391 from http://svn.asterisk.org/svn/asterisk/branches/10
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Merged revisions 372392 from http://svn.asterisk.org/svn/asterisk/branches/11


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@372393 65c4cc65-6c06-0410-ace0-fbb531ad65f3