Display 2d array as ASCII table

vim, 139 138 134

$x0xqq%ls<cr><esc>@qq@q:se nosol|%s/,/\t/g|%s/]/\t./|%!column -t -s'<C-v><Tab>'<cr>qwf";;h<C-v>GI|<esc>@wq@wll<C-v>Gls|<esc>0<C-v>Gs| <esc>:%s/"//g<cr>Yp:s/[^|]/-/g|s/|/+/g<cr>YggpkP

Accepts input in the form shown in the test cases. May or may not be valid, as this relies on the input string never containing any ", ,, ], or | characters.

If the input has to be able to contain ]s, then :%s/]/\t./<cr> can be replaced with qe$s<Tab>.<esc>j@eq@e for 2 extra chars. There is no easy way to allow ",| in the input.

Must be run in a Unix environment, as it relies on the column command line tool.

Slightly outdated explanation (by one revision, but that was just a bit of rearranging):

:se nosol<cr>    we need this later: G in visual block shouldn't go to BOL
$x0x             delete the surrounding pair of brackets
qq               record a macro
 %ls<cr><esc>    put each element of the big array on its own line
 @qq             recurse
@q               play back the macro until EOF
:%s/,/\t/g<cr>   replace all remaining commas with tabs
:%s/]/\t./<cr>   replace the ] at the end of lines with tabs and a dot
                 we need this for the line at the right edge of the table
:%!column -t     run the whole file through `column' on tabs
 -s'<C-v><Tab>
 '<cr>
qw               record another macro
 f";;            go forward 3 "s--that is, to the next "column"
 h               go back to the middle of the column
 <C-v>GI|<esc>   insert a line behind the cursor from top to bottom
 @wq             recurse
@w               play back until EOF
ll               move right before the line of dots we added earlier
<C-v>Gl          select the dots
s|<esc>          replace with a line (top to bottom)
0<C-v>G          select all the opening brackets
s| <esc>         again, (the leftmost) line
:%s/"//g<cr>     kill all the quotes around the data
Yp               duplicate bottom line
:s/[^|]/-/g<cr>  replace everything that's not a line with a dash
:s/|/+/g<cr>     now replace the lines with plus signs
YggpkP           put the separators before and after the first line

Thanks smpl for a byte!

JavaScript (ES6), 210 212 219

Edit 2 bytes saved thx @Neil

a=>(J=(m,j)=>j+m.join(j)+j,a.map(r=>r.map((c,i)=>s[i]>(l=c.length)?0:s[i]=l),s=[]),t=J(s.map(n=>'-'.repeat(n+2)),'+'),z=a.map(r=>J(r.map((c,i)=>' '+c+' '.repeat(s[i]+1-c.length)),'|')),z[0]+=`
`+t,t+J(z,`
`)+t)

TEST

F=a=>(
  J=(m,j)=>j+m.join(j)+j,
  a.map(r=>r.map((c,i)=>s[i]>(l=c.length)?0:s[i]=l),s=[]),
  t=J(s.map(n=>'-'.repeat(n+2)),'+'),
  z=a.map(r=>J(r.map((c,i)=>' '+c+' '.repeat(s[i]+1-c.length)),'|')),
  z[0]+='\n'+t,
  t+J(z,'\n')+t
)  

Z=[["License","2008-05-08","2009-03-11","2011-11-22","2013-08-12","2015-11-19"],["GPLv2","58.69%","52.2%","42.5%","33%","23%"],["GPLv3","1.64%","4.15%","6.5%","12%","9%"],["LGPL 2.1","11.39%","9.84%","?","6%","5%"],["LGPL 3.0","? (<0.64%)","0.37%","?","3%","2%"],["GPL family together","71.72% (+ <0.64%)","66.56%","?","54%","39%"]]

O.textContent=F(Z)

<pre id=O></pre>

CJam, 58 bytes

Anyone know trick of golfing in CJam?

q~z_{:,:e>)}%_{)'-*'++}%'+\+N+@@.{f{Se]"| "\+}}z'|N+f+1$f+